The various historical collections were fairly good:

Hopefully I'll be back in Sheffield one day, and will have time to play more next time.

I didn't quite know that Bletchley Park is actually separate from the National Museum of Computing (they are adjacent, but separated by a fence, needing an annoying 10-15mn walk all the way around), and Bletchey Park actually opens earlier, so it's probably best to visit first (also check the National Museum of Computing's website for which dsays they have guided tours and guides showing the hardware (well worth it).

I'll start with the National Museum of Computing as it was the most exciting to me with its fully functional rebuild bombe and colossus decryption machines for Enigma and Lorenz (the much more secure encryption system German Command used):

One big mistake the germans did was to send a weather report starting with the same german word (known plaintext) every morning. This allowed building a computer (bombe) that tried all rotor combinations to turn the crypted message into the known platintext:

The even more impressive machine (by a lot) was the aptly named "Colossus" which was build from scratch from a reverse engineered design (that part is so impressive), to decrypt the much more secure Lorenz encryption:

the computer reads the encrypted message from this paper tape (5 bit ASCII)

this machine did the decryption once the other machine had output the decryption parameters

How lorenz was reverse engineered and cracked is complicated and super impressive, but basically all came down to the almost same message being sent twice with the same key which allowed for a known plaintext attack:

This video shows the different machines in action Bombe rebuild (to break enigma), Colossus rebuild (to break Lorenz), plus the oldest still working half-mechanical computer (Harwell Dekatron):

And the museum had lot of other computers, a collection that is close to being as good as the one at the computer history museum in Mountain View, CA:

they have a whole collection of tubes (pre-transistors) to replace the ones that break on their machines

core memory

impressive they had so many of those machines, still working

I had one of those

this too

and this too (Asmtrad CPC464+memory upgrade+floppy)

didn't have this one at home, but worked with them at SGI

those I never had, but I wish I did. Archimedes was awesome and way ahead of its time with Arm RISC CPUs

The Harwell Dekatron was also a very cool (and still working) computer I had never seen:

Bletchley Park had different buildings each with their story and what they were used for:

Lots of info on the machines, an earlier crack of older enigma machines was to use EINS for plaintext attacks:

They had many displays on the brilliant mathematicians that broke the codes and built the machines. Alan Turing was one of them, but they were multiple others:

Despite some inefficiencies in having to go back and forth between the 2 museums to join a timed tour at Bletchley (which actually is skipable if you are short on time), I spent the entire day there (open to close) and it was very well worth it.

Thinkpad P73 vs P70, not a win all around: only one 2.5" drive instead of 2, and a badly designed power system

P70 vs P73, they look pretty similar

*Update*: it seems if that if you get a cheaper nvidia chip with the P73, it is then configured to accept 135W power supplies as the minimum required. That said, it will still refuse to work with any regular 90W power supply or external battery back, unless you force it with the center pin resistor swap.

While I have no plans to use windows on that machine, I thought I'd just try it out to see how it does on power. This is where I was impressed, windows can idle at less than 10W for more than 11H runtime, while I'm lucky if I can get linux at 15W. This is definitely a place where linux should do better, of course, it's not as if Lenovo put any work into making linux more efficient on their hardware either:

*Update* : with tlp and using the nouveau driver just enough to turn off the nvidia chip, I'm now able to tune the laptop down to 10W, almost matching windows.
See tlp issue 494 for details on how to setup tlp to run in low power mode when power is plugged in.

Another disappointment is that the P73 is mostly the same size and weight than the P70, but it has less room for storage. It has a bunch of empty spaces that aren't used for anything, and it can't use two 2.5" SATA drives anymore, like the P70 could. Worse, the now single 2.5" slot uses a lenovo only ribbon cable that does not ship with the laptop and basically means you cannot even add a 2.5" drive without that special ribbon cable, which isn't in stock yet. Well done... Ah yes, the battery is also not hot swappable, even if it is replaceable (unlike a Mac laptop where everything is sealed shut).

this shows the unobtanium lenovo cable for the now only single drive that fits, along the unused space

Ok, stop complaining, just buy a bunch of 170w or 230W power supplies and move on with your life

Tricking the P70 and P73 into accepting a power supply it wouldn't otherwise use

For the P70, I built this power supply adapter with a resistor bridge to tell the laptop how big it should think the power supply, is:

It's basically a configurable version of this. Yes, lenovo, I thank you for the hours I wasted opening up power supply plugs and replacing the center pin resistors:

Here's how the P73 responds:

- 230W works fine   4.6k => I have seen power supplies work with 170W but fail at 230W, so the laptop does draw more
- 170W works ok     1.9k (1.8k also ok)
- 130W rejected     1k
- 90W  rejected     550 

The rejected power supplies will be used to charge the laptop if it is shutdown, but they will not be used in any way otherwise. On the P70 the laptop would at least use the power supply to keep the laptop alive, and use half battery half external power supply. Not so with the P73, it just ignores it entirely.
This is utter bullshit as I have plenty of 90W power supplies, including 12V car converters, or a 90W external 20V battery pack I can't use anymore.

You can go read my Hacking a thinkpad slim tip adapter to output more than 90W (required to charge a Thinkpad P70) page for details, including this nice battery pack I couldn't use anymore:

*Update* : so, actually with some serious tlp hacking (basically I told it to force battery mode even if a power supply is plugged in), I've managed to throttle the laptop enough, even when plugged in, so that it only uses 20W. At that point, I'm actually able to use my old external battery pack, as well as a 90W power supply, as long as I lie to the laptop and pretend they are 230W power supplies with the resistor trick. In my tests with windows, it was not possible to throttle the laptop enough when plugged in, not to have it overwhelm a smaller power supply (not that 90W is small for a laptop that normally uses 20-30W when it's not charging batteries).
If you scroll to the bottom of the page, you'll also see a terrible buffer lipo hardware hack I did that allows to use the battery pack with higher amp draws, but it's a bit ridiculous (and bulky).
See tlp issue 494 for details on how to setup tlp to run in low power mode when power is plugged in.

Without the tlp hack or the buffer lipo hack, when I lie to the laptop and tell it is connected to a a bigger power supply, manage power draw with what I run, and disable battery charging in software, but the laptop will still draw the power supply for over 100W when you plug it in for a fraction of a second, and refuse it if the voltage drops.
Obviously this would not be a problem if the laptop simply had a 90W power supply mode where it throttle things down and turned off battery charging. This is mostly what the P70 does.

In the meantme, on top of hacking my power supplies, I also made this for my laptop, it looks silly and makes the thinkpad not look like a professional laptop, but well, that's lenovo's fault:

this takes any power supply and replaces the center tip resistor with a 1.9k one to emulate a 170W power supply

From talking to Lenovo, they don't think that this is really a problem, so since I'm an engineer, I made my own external battery pack, but I otherwise recommend to road warriors to avoid thinkpads from now on, given the backward power design in this one.

Making a Thinkpad P73 compatible external battery pack

Prototype with 150W step up converter which takes my 16V lipo to 20V while delivering enough amps to make the laptop happy:

it works, and the laptop thinks it's connected to a 230W power supply thanks to the center pin resistor.

Here's a quick demo:

Version 2 was to have a way to recharge the battery pack while it's being used. I've used this to use the battery pack as a buffer to absorb peaks from the laptop without tripping an external power supply, including in a car limited to 100W or a plane power supply limited to even less:

this works in theory, but the lipo charger is quite slow and wouldn't keep up for long, but I made a better version shown lower down

Lenovo's P73 airplane mode simply stops using the external power supply and reverts to batteries. Sigh...

Making a battery pack to act both as buffer for a smaller power supply, and as emergency external power (even power the laptop from 12v)

version 1 was a bit bigger than I wanted, 90W power supply shown for scale

here, the 90W power supply is recharging the battery at 2.5A while it's being discharged at 3A on the output side, using the battery as buffer

I made version 3 a bit smaller, with a built in 12V lipo to act as buffer for a smaller power supply. Yes, it's a beautiful piece of art, I know :)

Pushed to the extreme, I can now use my original external battery pack again by having it recharge my lipo+150W step up that can output more amps than the ravpower pack can. Of couse, it's inefficient, the ravpower pack outputs 20V that gets down converted to 12V by the H605 Air lipo charger, which charges the built in 3S lipo in the box, and then gets up converted back to 20V without the amp limitation (the phone used to control the lipo charger also inside the box):

The really cool thing is that by using tlp, it's actually possible to tune the laptop down to very low power use, even when plugged in, something that windows probably can't do:

7.3W with the screen off (and around 10W with wifi off and the screen on low dim) is not bad for a laptop that big

4S Lipo vs 4x 18650 or 26650 batteries

That said, as I recently found out that 16650 (or better 26650) batteries are both lighter and smaller. The only thing the lipos do, is offer a better discharge rate, but while that's useful for a high power RC plane motor that can empty the batteries in 10mn, it's not needed for a laptop:

26650s are 195 Wh/kg while the lipo I gave was 184Wh/kg. The 3rd battery listed is supposed to be 260Wh/kg which is much nicer, that said, it looks like those samsung batteries are actually smaller than 26650s, lighter, and yet offer the same 5Ah at 3.6V. If so, that's very impressive.

As of this writing, I have however not found 26650 battery holders that hold 26650 protected cells that are a bit longer. This seems to the be only one available, and it's too short to hold the batteries: https://www.amazon.com/gp/product/B074GVPWSH

A few months later, I ended up cutting them and taping them to make them longer. It doesn't work great, but it was enough for a few tests. In the end, I found that somehow I wasn't getting enough amps out of them, which surprised me, so they didn't work that well compared to a lipo:

Conclusion

However, when I got my thinkpad P70, although it also uses around 25W in typical use, which means plenty of extra wattage on a 90W power supply to charge the battery, the P70 was unfortunately designed not to charge under any condition unless it recognizes a power supply that's at least 135W (it ships with a 170W power supply, and it's a huge monster brick). I'm pretty mad at lenovo for that because they could totally have designed the P70 to charge at a slower rate from a 90W power supply, or at least when the laptop is sleeping, but no, even when it's sleeping, it will just not charge at all. Sadly, this means that the RAVPower 23000mAh Portable Charger Power Bank External Battery Pack I bougght, was able to power the laptop, but not charge it. I guess in this case, it's not a huge issue since energy would be wasted trying to charge the laptop battery instead of just powering it, but still, that was disappointing.

here, the pack is powering my laptop at 20V, 2.1A

The P70 will function off a 90W power supply by just not discharging its battery, and consuming around 1.5A at 20V (i.e. 30W), so that meant that not only I had to buy some bulky 135W power supplies (less bulky than 170W thankfully), but also that I was now unable to use my travel iGo 110W 12V DC power supply, which I use to charge in cars. For AC, I did buy a Lenovo ThinkPad 135W (Slim Tip) Replacement AC Adapter for lenovo ThinkPad T440p 20AN 20AW, Lenovo ThinkPad T540p 20BE 20BF: https://www.amazon.com/gp/product/B00HOMBO0M

But for car use, I was upset about the situation, so I read up and realized I only had to change the resistor in my barrel connector to slimtip adapter and that would likely allow my thinkpad to start charging from my 110W iGo power supply. The hard part was finding where the resistor was since I had to replace a small resistor with a bigger one (the other way around, I could have trivially added a resistor in series).

So, I started with the AC Charger Power Supply Adapter Converter Cable Cord For Lenovo ThinkPad : https://www.amazon.com/gp/product/B00T013J44 and had to find where the resistor was hidden. After cutting the cable in 2, I convfirmed it was on the slimtip side, so I had to take the plug apart until I found it.

After that, it was just a matter of adding a new resistor, and in the end, I added a resistor bridge, so that I could select no resistor, 550 Ohm (90W), 1kOhm (135W), or even 1.9kOhm (170W). For my laptop, though 135W was enough, and my iGo only delivers 110W anyway.

I added a amp/volt meter (RioRand 2in1 4.5-30V 10A Digital Voltage Detector DC Current Volt Amp Meter), so I can tell how much current is flowing and whether I might be exceeding the wattage of the power supply. When my laptop is running, and the battery charging, it's now using 5.6A (just about 110W)

So problem solved. I'm not super happy at Lenovo for having stupidly designed their Thinkpad P70 not to charge from a 90W power supply under any use case, even at reduced speed, or even with the laptop sleeping or off, but since I already had the laptop, I was stuck with it, so this little resistor hack did the trick. Hope this helps someone.

Oh yeah, for car use, instead of this old obsolete iGo brick, I made my own 12V-20V DC-DC converter, and you can read more about it on this page

So let's be honest and say that it is a big a heavy laptop, but that was an acceptable tradeoff for me. CPU wise, it's actually no faster than the T540, but the big new thing is the 2 M2 slots in addition to capacity for 2 2.5" Sata drives, like the T540 (one goes in place of the DVD Burner using a special tray).

yes, it's big

the 2 M2 slots are on the right, and the 2nd drive goes under where the SSD is visible in this picture

size of M2 sticks compared to the SSD (with free shot of the 96Wh battery :) )

Comparison with the T540

So the P70 can currently house 5TB of storage and I was interested to see how well the M2 slots worked compared to the Sata ones under linux. First thing to note is that currently M2 slots can only house 512MB of storage each vs 2TB for the 2.5" Sata slots that have more room. Sadly, Lenovo is still not selling the Drive Caddy Adapter for the P70, but the good news is that you can buy this $17 Soogood 2nd HDD SSD Hard Drive Caddy Adapter Use For Lenovo Thinkpad T440p T540p W540p from Amazon, unscrew the little tab from the DVD Drive, screw it on the drive caddy adapter, and it'll work in the P70.

To try that out, I got the following (with price by GB as of 2016/02), in increasing price per GB: - 4.6c/GB: Seagate 2TB Laptop HDD SATA 6Gb/s 32MB Cache 2.5-Inch Internal Bare Drive (ST2000LM003) - 30c/GB: SATA6G: Samsung 850 EVO 2 TB 2.5-Inch SATA III Internal SSD (MZ-75E2T0B/AM) - 33c/GB: M2/SATA Samsung 850 EVO 500 GB M.2 3.5-Inch SSD (MZ-N5E500BW) - 64c/GB: M2/NVMe: Samsung 950 PRO -Series 512GB PCIe NVMe - M.2 Internal SSD 2-Inch MZ-V5P512BW

So it's interesting to note that SSDs still cost 6.5x more than a hard drive (actually I was surprised to see how cheap the 2.5" 2TB hard drive was). Next, it's good to know that M2/Sata SSDs cost about the same price per GB than full size Sata SSDs. And last, at twice the price, the M2/NVMe SSD is no bigger than the SATA M2 version, but clearly more expensive. It's supposed to be up to 4 times faster in bulk transfer rate due to the use of 4 PCI lanes, but I was curious to see how much faster it would actually be for real use with linux.

First, is looking at support. To make things interesting, I decided to make the NVMe SSD my boot drive. The Thinkpad bios of course supports it fully, but a big gotcha is that it'll only boot if you use a GPT partition with EFI. Setting that up from scratch was a pain, but I got through it, and it's out of topic for this post.

Next, is linux support. Thankfully linux has supported NVME for a while now. I just set CONFIG_BLK_DEV_NVME=y in my kernel so that I didn't have to worry about the module being in my initrd. Device partitions show up as /dev/nvme0n1p1 and so forth.

Now, the benchmarks. For my main filesystems, I have btrfs on top of dmcrypt, created with:

cryptsetup luksFormat --align-payload=8192 -s 256 -c aes-xts-plain64 /dev/device

In the tests below, I did used hdparm, iozone, and 2 kinds of dd, ddd with data, and dd0 copying just /dev/zero:

ddd test: sync; dd if=/mnt/ram/file of=file bs=100M count=100 conv=fdatasync; dd if=file of=/dev/null bs=100M
dd0 test: sync; dd if=/dev/zero of=file bs=100M count=100 conv=fdatasync; dd if=file of=/dev/null bs=1M

Let me start with the summary conclusions first, since this is what most people probably care about:

More detailled summaries related to the test results below:

So there you go. I realize that my test suite may not have been perfect, but hopefully the results are helpful to others. I'm hoping linux will get fixed, or that I can find a tunin g parameter to bridge the gab in cached IO speed between Sata 6G 2.5" and M2 slots. Below are test results in more details are you go down the page.

Here are test results for cached IO:

		SATA/M2 dmcrypt	 SATA/M2	NVMe dmcrypt	NVMe		SATA6GB/dmcrypt
hdparm -t	 534MB/s	 517MB/s	1307MB/s	2140MB/s	 534MB/s

ddd 10GB read	 550MB/s	 560MB/s	2000MB/s	2400MB/s	 550MB/s
ddd 10GB write	 500MB/s	 503MB/s	1300MB/s	1200MB/s	 506MB/s

dd with /dev/zero hits optimizations that actually penalize NVMe:
dd0 10GB read	   7GB/s	 6.7GB/s	 2.3GB/s	 4.4GB/s	 6.6GB/s
dd0 10GB write	 495MB/s	 503MB/s	 1.3GB/s	 1.3GB/s	 2.0GB/s

iozone -e -a -s 4096 -i 0 -i 1 -i 2 (cache makes Sata6G faster than M2, weird):
ioz read 4KB	1760MB/s	1790MB/s	 675MB/s	 766MB/s	7863MB/s
ioz write 4KB	 268MB/s	 298MB/s	 295MB/s	 291MB/s	 777MB/s
ioz ranread4KB	5535MB/s	7392MB/s	3185MB/s	7261MB/s	7892MB/s
ioz ranwrite4KB	 288MB/s	 329MB/s	 205MB/s	 381MB/s	 796MB/s

For comparison, I then used directio to bypass the caching layer:

iozone -I -e -a -s 4096 -i 0 -i 1 -i 2 (direct IO):
		SATA/M2 dmcrypt	 SATA/M2	 NVMe dmcrypt	 NVMe		 SATA6GB
										 dmcrypt notcrypted
		 btrfs		 btrfs   ext4	 btrfs		 btrfs   ext4	 btrfs     ext4
ioz read 4KB	 255MB/s	 303MB/s 408MB/s 303MB/s	 396MB/s 562MB/s 310MB/s 379MB/s
ioz write 4KB	 195MB/s	 238MB/s 344MB/s 257MB/s	 358MB/s 361MB/s 233MB/s 365MB/s
ioz ranread4KB	 305MB/s	 351MB/s 482MB/s 476MB/s	 699MB/s1434MB/s 309MB/s 475MB/s
ioz ranwrite4KB	 265MB/s	 223MB/s 392MB/s 260MB/s	 217MB/s 315MB/s 254MB/s 366MB/s

Details of each test, per type of drive;

===============================================================================
saruman M2 SATA 512GB encrypted btrfs

saruman:/tmp# hdparm -t /dev/mapper/cryptroot
 Timing buffered disk reads: 1604 MB in  3.00 seconds = 534.03 MB/sec

iozone -e -a -s 4096 -i 0 -i 1 -i 2:
                                                              random    random
              kB  reclen    write  rewrite    read    reread    read     write
            4096       4   257076   281089  1761711  6094733  6066754   290373
            4096     512   277108   295167  1588844  8426437 11128258   318731
            4096    4096   268940   308248  1760087  8062616  8377131   320802

iozone -I -e -a -s 4096 -i 0 -i 1 -i 2:
            4096       4    38626    45227   102236   111141    30936    64317
            4096     512   138467   128878   134674   137832   140067   126248
            4096    4096   195439   273100   255379   307300   305605   265093

saruman:/mnt/mnt# sync; dd if=/dev/zero of=file bs=100M count=100 conv=fdatasync; dd if=file of=/dev/null bs=1M
10485760000 bytes (10 GB) copied, 21.1761 s, 495 MB/s
10485760000 bytes (10 GB) copied, 1.49373 s, 7.0 GB/s

kernel 4.4.1 make -j8:
real    17m54.712s
user    126m26.620s
sys     6m21.948s

btrfs send/receive encrypted partition to non encrypted, 87GB: 10mn30

saruman M2 SATA non encrypted btrfs
-----------------------------------
saruman:/mnt/mnt4# hdparm -t /dev/sdc4
/dev/sdc4:
 Timing buffered disk reads: 1554 MB in  3.00 seconds = 517.93 MB/sec

iozone -e -a -s 4096 -i 0 -i 1 -i 2:
                                                              random    random
              kB  reclen    write  rewrite    read    reread    read     write
            4096       4   285020   297565  1739944  7434579  6605595   305785
            4096     512   310937   336617  1298278  3703511  5483860   299416
            4096    4096   298433   317101  1790911  7392988  7434579   337476
iozone -I -e -a -s 4096 -i 0 -i 1 -i 2:
            4096       4    47219    93497   118900   126065    39160    86462
            4096     512   214381   213388   194307   209215   206951   209289
            4096    4096   238792   221839   303768   352951   351342   223618
ext4 iozone -I -e -a -s 4096 -i 0 -i 1 -i 2:
            4096       4   119524   146035   150173   159105    53090   140697
            4096     512   358954   354810   366466   423088   419760   375542
            4096    4096   344087   398828   408259   478337   482569   392487

saruman:/mnt/mnt3#  sync; dd if=/dev/zero of=file bs=100M count=100 conv=fdatasync; dd if=file of=/dev/null bs=1M
10485760000 bytes (10 GB) copied, 20.8537 s, 503 MB/s
10485760000 bytes (10 GB) copied, 1.55651 s, 6.7 GB/s

kernel 4.4.1 make -j8:
real    17m55.612s
user    126m31.952s
sys     6m27.452s

********************************************************************************
saruman M2 NVMe 512GB encrypted btrfs

saruman:/tmp# hdparm -t /dev/mapper/cryptroot2
/dev/mapper/cryptroot2:
 Timing buffered disk reads: 3924 MB in  3.00 seconds = 1307.56 MB/sec

iozone -e -a -s 4096 -i 0 -i 1 -i 2:
                                                              random    random
              kB  reclen    write  rewrite    read    reread    read     write
            4096       4   284205   341651   742181  6195843  6178018   341101
            4096     512   314351   319573   864883  8865630  8902382   384993
            4096    4096   295741   201042   675234  3281854  3185110   205974
iozone -I -e -a -s 4096 -i 0 -i 1 -i 2:
            4096       4    80042    83160   122616   127129    41421    53963
            4096     512   168713   153333   167710   209923   198123   168026
            4096    4096   257968   258566   303023   490828   476440   260014

saruman:/mnt/mnt2# sync; dd if=/dev/zero of=file bs=100M count=100 conv=fdatasync; dd if=file of=/dev/null bs=1M
10485760000 bytes (10 GB) copied, 8.01494 s, 1.3 GB/s
10485760000 bytes (10 GB) copied, 4.63397 s, 2.3 GB/s

kernel 4.4.1 make -j8:
real    17m57.513s
user    126m58.360s
sys     6m25.164s

btrfs send/receive encrypted partition to non encrypted, 87GB: 7mn
(33% faster than Sata M2)

saruman M2 NVMe non encrypted btrfs
-----------------------------------
saruman:/mnt/mnt4# hdparm -t /dev/nvme0n1p4
/dev/nvme0n1p4:
 Timing buffered disk reads: 6422 MB in  3.00 seconds = 2140.38 MB/sec

iozone -e -a -s 4096 -i 0 -i 1 -i 2:
                                                              random    random
              kB  reclen    write  rewrite    read    reread    read     write
            4096       4   274808   271851   684271  2634219  2280673   177630
            4096     512   290191   336755   668196  3362795  4039655   184779
            4096    4096   291427   340345   766588  7355007  7261741   381768
iozone -I -e -a -s 4096 -i 0 -i 1 -i 2:
            4096       4    94814   117116   147645   159695    44075   108039
            4096     512   271130   267800   239969   325933   301841   271062
            4096    4096   358602   275933   396591   719099   699939   217665
ext4 iozone -I -e -a -s 4096 -i 0 -i 1 -i 2:
            4096       4   107281   200735   205900   263035    54832   124219
            4096     512   537478   374641   525060  1173664  1139338   558807
            4096    4096   361545   526137   562632  1483477  1434069   315883

saruman:/mnt/mnt4# sync; dd if=/dev/zero of=file bs=100M count=100 conv=fdatasync; dd if=file of=/dev/null bs=1M
10485760000 bytes (10 GB) copied, 7.90653 s, 1.3 GB/s
10485760000 bytes (10 GB) copied, 2.35863 s, 4.4 GB/s

kernel 4.4.1 make -j8:
real    17m54.221s
user    126m46.264s
sys     6m10.592s

********************************************************************************
saruman Samsung Evo 850 2TB SSD encrypted btrfs

hdparm -t
 Timing buffered disk reads: 1606 MB in  3.00 seconds = 534.87 MB/sec

iozone -e -a -s 4096 -i 0 -i 1 -i 2:
                                                              random    random
              kB  reclen    write  rewrite    read    reread    read     write
            4096       4   513924   738957  8586475  9144037  8017464   697665
            4096     512   772100   820362  9287391 10136778 10586522   840551
            4096    4096   719099   777517  7863339  8047509  7892238   796108

iozone -I -e -a -s 4096 -i 0 -i 1 -i 2
            4096       4    76626    47961    92886    80947    36063    63788
            4096     512   135087   138998   143127   150981   144393   132219
            4096    4096   233245   234058   310797   311552   309855   254080

ext4 iozone -I -e -a -s 4096 -i 0 -i 1 -i 2 (unencrypted)
            4096       4   118013   141212   130575   111534    42343   138654
            4096     512   336347   312192   332847   414404   424542   342707
            4096    4096   365227   364638   379298   484160   475122   366536

saruman:/tmp# sync; dd if=/dev/zero of=file bs=100M count=100 conv=fdatasync; dd if=file of=/dev/null bs=1M
10485760000 bytes (10 GB) copied, 5.23919 s, 2.0 GB/s
10485760000 bytes (10 GB) copied, 1.58287 s, 6.6 GB/s

kernel 4.4.1 make -j8:
real    16m4.305s
user    104m0.816s
sys     7m2.832s

This is what it looks like:

I analysed how the DS10A worked, and due to sheer luck in its design, the wires going to the magnetic sensor turn out to be ground and signal, and the water sensor conducted enough current between them to allow triggering of the DS10A:

Wiring is totally trivial, you only need to use a 3rd wire connected to the plus from the 2 batteries, and it "just works". For extra credit, I wired a buzzer between signal and ground, and my water sensor passed enough current to allow the buzzer to run.

I used the Phantom YoYo High Sensitivity Water Sensor which was $10, but apparently you can get one that should work too from seedstudio for $3

The DS10A, I have a stack of, which you can sometimes find on ebay for cheap in bundles, and my house is already wired to receive those signals, so it was trivial to generate an Email and page from misterhouse when this sensor got triggered.

With my new roomba, I even setup 3 zones with virtual walls, and I really wanted to have an idea how long my roomba went out to see how much work it was doing and how its battery was doing over time.

In the end, I ended up using a DS10A door/window sensor and glued a magnet on top of my roomba, which closes the contact when it goes back to its dock. I then have misterhouse code that kept track of how long I left my doors opened to also keep track of my roomba and long it goes to work, as well as warn me if it doesn't make it back to its dock after too many hours:

My mailbox now shows:

Chg: Roomba Just Left                                    
Chg: Roomba Just Returned after 41.1 mn                  
Chg: Roomba Just Left                                    
ChgTmr: Roomba Left longer than 300 mn                   
Chg: Roomba FINALLY Returned after 2881.1 mn             

That way, I know when the timer worked, how long my roomba worked, and whether it got stuck somewhere or not. Ok, it'snot perfect, it would be nice to know when it crossed the zones, and how long it ran before getting stuck. This sounds a lot more involved though, maybe later.

I hearby want to thank Wansview for giving me some of the above cameras for review (I bought some of them on my own, and after seeing my reviews, they asked me to test and review a few more). Note that while wansview cameras do not offer the sharpest 1080p pictures I've seen (Zavio and FI9900 win, even I hate foscam), the nice things I've written on wansview are not based on the free cameras, but the fact that they have always answered my support queries, including the technical ones showing issues with the firmware, and fixed the firmware after that (including making it work on linux and other other operating systems), while Foscam tells people that they're running the wrong version of windows, and that's it.
zavio truly sells good cameras, but sadly they cost more than double, which may be a bit out of reach for many people.

Zoneminder

One good page to know about is ispyconnect, which gives all the entrypoints for many cameras:

Camera in 2009

Dlink DCS900

Cameras in 2013/11

Foscam FI8904W

Wansview NCB541W

Foscam FI8910W

Because it wasn't wide angle enough, I got a 3rd party (cheap) wide angle F2.0 lens for it. It blurs the picture around the edges quite a bit, but gives me the shot I wanted:

Foscam FI8920W

Foscam FI8921W

I also changed the F2.8 lens to a wider dealextreme F2.0 lens that's blurry around the edges:

Ubnt Aircam

out of focus out of the box, this is kind of sad

this is only barely better than the 480p version but great wide angle

480p picture blown up to 720p to compare with 720p 'native'

Edimax 3115w

Zavio F3210

Cameras in 2015/08

Foscam FI9826PB

Foscam FI9805P

Foscam FI9900P

Anyway, here's what I found on the Foscam 9900:

If you guessed that I think Foscam sucks by now, you guessed right. First to me, they look like liars and cheaters by what really looks like buying fake reviews on amazon, and then in the last 2 years, they actually made their web interface worse since the FI8921W where you could at least login on linux and change settings.

While I'll repeat that life is too short to deal with this crap and give money to that company, I used jpeg URL ( /cgi-bin/CGIProxy.fcgi?cmd=snapPicture2&usr=user&pwd=pwd1 ) to make it work with zoneminder, and it works well enough. As other reviews have said, the optics are actually quite good, I do like the very wide angle picture without barrel effect:

Too bad that Foscam's firmware sucks so much, the optics are good now. If you need an outdoor camera, and value your time and sanity a few dollars, I'd recommend the Zavio B6210. If an indoor camera used outdoors with light weather proofing is good enough, try the cheaper and somewhat better Wansview NCM625GA/Q1 below (although its picture isn't as wide and show barrel effect):

Wansview NCM625GA (aka Wansview Q1)

Cons:

Pros:

Updates:

Info:

The 1920x1080 shots are truncated to 1280 for display on this page

Wansview NCM751GA (aka Wansview W1)

This camera was superseeded by the Wansview W2 which is both much smaller and cheaper. Honestly, the only advantage of the W1 is the onboard storage if you care about that. For remote capture support, the W2 will be a much better bet (and almost half the price).

The viewing anble is pretty narrow. That's either a good or a bad thing depending on your needs, but if you need wide, prever the NCM625GA if you can put it outdoors safely, or consider the foscam or a higher priced camera. The night vision is decent though:

The 1920x1080 shots are truncated to 1280 for display on this page

My camera was giving blurry pictures because the lens was mis-adjusted. I had to open it up and readjust the lens for the picture to a bit more clear.

Like the NCM625GA, it now comes with firmware that works fine with linux and any operating system, and the android app gets the camera working in no time after you scan the QR code.

Wansview K1

It's a great little camera. Just like its big brother, I installed the recommended iSmartViewPro on android, scanned the QR code on the back of the camera, and had it working instantly. The picture quality is very good and this is the widest picture of any camera I've reviewed so far (even if it comes at the price of barrel effect).
Please refer to my Wanview NCM625GA review for configuration details. The only real downside is the placement of the ethernet jack, making it hard to fit some ethernet cables unless you remove the flexible sleeve, but that's a manageable problem :)

If you have firmware 0.39 or 0.40 and install this firmware patch I got from Wansview (via the web upload interface), http://ipaddr/mjpeg/snap.cgi?chn=0 now returns a proper Content-Type: image/jpeg header and will work with Zoneminder and other software that expects a jpeg. If your firmware is 0.41 or later, it should just work without the patch.

It is the best 1080p camera you can get for that price, I'm quite impressed with it.

The 1920x1080 shots are truncated to 1280 for display on this page

Wansview W2

My camera shipped with firmware 0.42 which supports http://ipaddr/mjpeg/snap.cgi?chn=0 out of the box with a proper Content-Type: image/jpeg header and will work with Zoneminder and other software that expects a jpeg.

This is definitely a good alternative to the Foscam FI9900 if you are ok with a narrow lens in exchange for better firmware froma better company. However I'm not going to lie, the picture is not ultra sharp. It doens't look blurry but it feels like the sensor is not truly 1080p, or something is robbing a bit of resolution or sharpness.

The 1920x1080 shots are truncated to 1280 for display on this page

Wansview Q2

My camera shipped with firmware 0.42 which supports http://ipaddr/mjpeg/snap.cgi?chn=0 out of the box with a proper Content-Type: image/jpeg header and will work with Zoneminder and other software that expects a jpeg.

The Q1 picture is a bit more narrow and looks a bit more sharp

The Q2 picture is a bit wider and bit less sharp

Here are the other Q2 screenshots, they look fairly good at night;

Reolink RLC-410

Setup was a breeze, the one downside is because it's a PoE camera, it does support 12V input, but it does not ship with a 12V power supply. Thankfully I have a drawer full of those :)
The default picture was way too bright (over exposed) and the sharpening was turned up too high, making the picture grainy. On the last picture, I turned the brightness down as well as the sharpening, and the results are better. The lens is about as wide as Wansview Q2. *Update* a firmware update seems to have dramatically improved the picture quality, which to be honest, was pretty poor. The screenshots below are the old picture quality, I have not had the chance to get shots with the new firmware yet since my camera is installed outdoors at the moment.

Here are screenshots (resized to 1280, but you can click on them to get the full original size). Again, these are very poor quality and a new firmware fixes those:

Wansview K2

So, for that limited price, you still get most of the typical wansview interface without any sdcard or recording support, but you can tell the CPU is slow. It's slow enough that you have to wait for the web page to load, and also slow enough that a reboot takes a while. Last, but not least the picture is only 720p, not 1080p, and when comparing a downsided picture from a K1 and a native 720p picture from the K2, the K2 picture is not as sharp but still very usable
It's far from a perfect camera, but again, you only paid $30 (my favourites from Wansview are definitely K1 and Q1). If you want a camera that's more capable, the K1 is a very good small camera, so get that one instead. The choice is yours :)

Here are the screenshots in native 720p:

Using cameras outdoors

Foscam FI9821W and Zavio F3210, along with an IR booster for better distance vision at night with the Zavio

we don't exactly have harsh winters here, or really bad rain, so part of my equipment is just outdoors under the gutter

I then have ethernet and power going in my yard to the malibox

I do use a waterproof box for equipment outside (includes an insteon iolinc to control the mailbox and flood light if you open it)

very tight fit, but I used a 7A 12V power supply to power the gigabit switch, floodlight (12V LEDs), and 4 IP cams

this should take care of any mailbox thieves :)