Marc's Public Blog

The conf had plenty of talks to see, and great parties. Just a few pictures below to give a taste, and I also have a lot of pictures of my visiting of San Diego.

A few pictures from the keynotes:

kernel panel

A few slides from talks:

And we had some nice parties. The first night was a rooftop party:

The second evening, we had a party on an almost-island, including a small cruise to get there:

The 3rd evening, we had a beach Hawaiian party on Coronado Island, which was quite good:

the long bridge that gets you there

A few random picts from the conf:

It was a good conf and a great time.

It's the best aircraft carrier I've ever visited. They show you a lot more than the average boat, you see 4 levels of decks, and the inside of the city on the sea.

you can go to church

multiple dining rooms

multiple medical facilities

ER room

dentist

After seeing le down levels I had never seen before, it was time to go on the main deck:

San Diego view from the aircraft carrier

I had a bit fewer than 3 hours, which wasn't long enough to see it all without rushing. It's definitely the best aircraft carrier I've visited.

Flying there was "interesting" since the plane I was about to take failed preflight and I had to switch planes at the last minute. Interestingly, by then the overcast had actually gotten worse and the hole I was going to aim for had closed, so I just left IFR, which was pretty painless.

I got there a bit late, 08:35, but just in time to get ready for my session at 09:00 and go.

Dave got to drive one of Andy's cars. I'm told he didn't hate it too much :)

Stephen taking his NSX for the first time

Gassing up before the next session.

The flight home was uneventful:

haha, that was a good one

Here's a session I did:

And for the last session, I put my GoPro in the McLaren that Dave was driving to give rides:

It had been a while (almost 15 years?) since I had been to the aquarium on Pier39, but I remembered it was pretty nice and obviously conveniently located, so I suggested we went there. It was a nice visit

these jellyfish always make for great pictures

that octopus managed to reshape its body to get inside the beaker through the small hole

After that, we went to visit the rest of Pier39 shops:

boudin, strange name for a bakery :)

We then went for a small cruise around the bay to the golden gate and around Alcatraz

I just learned that James Lick (the rich guy who donated money that built the Mt Hamilton Lick observatory) told his friend Ghirardelli he should come to San Francisco to sell chocolate. I guess that worked out :)

Alcatraz

those ships are huge

We finished the day by having a quick look at San Francisco before going for a dinner magic show:

Peter Morrison gave us a good magic show at the Marrakech Magic Theater, which was a good way to end the evening:

Since I grew up seeing magic shows, I can be a tough public, and I thought they did a really good job, their show was enjoyable.

They have a new deal where they work with restaurants to perform there while people get dinner, and that worked out pretty well. If you're thinking about going, do get tickets from him directly though they're cheaper than the online offers and he gets to keep the money that would otherwise be lost to those ticket sites.

The balloon trick was fun

Dan also did close up before and after the show, in addition to his show

His web site is http://www.danchanmagic.com/ if you want to go see him or hire him.

Not that I'm supposed to be good at golfing since I don't golf, but I won again ;)

Please also read this very good report from Luke on SSD unreliabilities.

Crucial C300 sudden death and full data loss

So, before people tell me "you should have bought intel", I got the C300 from work and installed it because I trusted it had been pre-qualified and was good. Turns out, I was one of the people doing the pre-qualifying :) Later, I did look at intel for my drives, but they were lacking in size capacity when I was looking for 512GB and later for 1TB. Too bad because they've been shown to be the most or amongst the most reliable drives so far.

I wasn't using TRIM with the C300 at the time, because it's not necessarily recommended if you use dm-crypt ( http://asalor.blogspot.com/2011/08/trim-dm-crypt-problems.html ). The C300 likely did not appreciate that I filled it a few times and that it had to use its garbage collection algorithm to reclaim blocks (when it was getting full, it was very very slow, as in 100x slower than a spinning drive at times).

In the end, it died after fewer than 3 months of use, where it just disappeared from the SATA bus. Some magic 'plug the power but don't do data' for 20mn or so, several times, brought it back (after several days of trying) long enough for me to see it could still talk SATA and that all my partitions and data were gone. Even then, I wasn't able to really usefully talk to it anyway.

If you read up on this, and hear Crucial support recommending that you let the drive sit at the bios for 20mn once it a while so that its garbage collection can kick in after 15mn of it not being used, you'll understand that you should run away in the other direction rather than buying one of those drives: http://forums.crucial.com/t5/Solid-State-Drives-SSD/Bios-is-not-recognize-crucail-m4-SSD-64GB/td-p/63835

Maybe the C400 sucks less, but once burnt, twice shy, and the C300 was so bad, that I just don't trust Crucial to write proper firmware at this point.

Samsung 830 512GB severe random IO slowness with linux and windows

So, I then did some reading about SSDs and shopping around. I found that the Intel did not come in 512GB (it was a bit smaller), and that while Intel ruled SSDs early on, it hasn't kept up in performance and offerings. Also, they use older sanforce controllers that do not do well with software encrypted data (exactly what I had).

From online reading, the next best player was Samsung, so I got an 830 512GB drive from them, and was quite hopeful after reading reviews and how they designed and manufacture all the parts themselves.
That decision came back to bite me. I spent too many hours (between 10 and 20) with samsung tech support, doing many benchmarks, and working with the linux community, because its random IO performance was bad. How bad? Well, how does 5 times slower than my hard drive in the same laptop sound?

On time spent with the linux community debugging this with multiple filesystems, laptops, and tweaks, I'm not kidding. See a small sample:

There is one problem that might be linux specific: the drive is very slow for encrypted block device access without:
blockdev --settra 8192 /dev/mapper/cryptroot

But past that, I found no other problems, and replicated the problem with ntfs, and even after putting the SSD in a windows desktop with Windows 7 64bit. Samsung's old Benchmark registered so low on their own Random IO test that the bar graph showing speed was a single line at the '0' mark.
Samsung support had no idea why I saw this. They suggested I get another drive in case mine was bad.
The new drive had identical problems and in the end I had to return both. Yes, the drives had the latest firmware. The test below shows lower block IO because it was on SATA2, not SATA3 like in my laptop but I was only worried about Random IO.

I have no idea why those drives were so unexplainably slow on random IO reads (not even writes) when block IO was fast (500MB/s). I don't know how they work for others, but they failed to perform for me on 3 machines, 4 filesystems, and 3 operating systems.

That was a lot of time wasted, and I'm not impressed with Samsung anymore :(

Samsung 840 Evo 1TB (bought in November 2013)

Non surprisingly, it's the fasted drive of them all, but it's over a year newer. With an upgrade to linux 3.11 in the meantime, encrypted btrfs on that drive is almost as fast as native raw speeds.

OCZ 512GB Vertex 4 vs Samsung 830 512GB vs Samsung 840 EVO 1TB linux tests with btrfs, ext4, and dmcrypt

Update: the drive is fast, it never really lost data (except apparently the last few blocks written before locking up), but I had 3 drives eventually go into a mode where they lock up and my laptop needs to be power cycled under certain workloads (mencoder is one for me). They always recovered, only lost the last bits of data being written when the drive locked up, but that's just no good. I replaced the drive 3 times and eventually switched to a 1TB Samsung 840 Evo.

Old text from July 2012:
After more research still, this drive came highly recommended too. It's the fastest from OCZ and the most expensive (they have slower cheaper ones). And yet, the most expensive one was $100 cheaper than the Samsung, and 36 times faster for random IO reads. Oh, also the OCZ has 5 year warranty instead of 2 for Samsung.

There are only crude tests, but they are the ones that mattered to me to validate that the OCZ didn't have severe problems in my hardware like the Samsung 830 did.
Here are optimizations I used:

The OCZ was upgraded to Firmware Version 1.5, and the Samsung 830 claimed to have the latest firmware as of 2012/08 (that was version CXM03B1Q as reported by smartmontools). The Hitachi Hard drive in my laptop is a slow 5400RPM model.

Long story short, the OCZ is super fast, worked great in my tests, and was cheaper than the Samsung and the Crucial. Win all around.

Scanning 15K inodes with the Vertex 4 (vs Samsung and spinning hard drive)

Summary of results:

                                        OCZ Vertex 4 512GB | Samsung    | Samsung    | Hitachi HD 
                                                           | 830 512GB  | 840 1TB    | 1TB 5400 RPM
---------------------------------------------------------------------------------------------------
Encrypted BTRFS:                                           |            |            |
reset_cache; time du -sh src                               |            |            |
514M        src                                            |            |            |
real                                                0.959s | 25.741s    | 0.53s      | 5.252s
                                                           |            |            |
Unencrypted btrfs                                          |            |            |
mount -o compress=lzo,discard,nossd,space_cache,noatime    |            |            |
reset_cache; time du -sh src                    kernel 3.5 | kernel 3.5 | kernel 3.11| kernel 3.5
514M        src                                            |            |            | 
real                                                0.636s | 24.937s    | 0.11s      | 1.007s
                                                           |            |            |
Unencrypted ext4                                           |            |            |
mkfs.ext4 -O extent -b 4096 -E stride=128,stripe-width=128)|            |            |
mount -o discard,noatime /dev/sda2 /mnt/mnt2               |            |            |
reset_cache; time du -sh src                               |            |            |
519M        src                                            |            |            |
real                                                0.289s | 12.459s    | 0.21s      | 0.380s

Block Reads on Vertex 4 and Samsung 840 EVO (vs Samsung 830 and spinning hard drive)

Summary:

                                   OCZ Vertex 4 512GB | Samsung      | Samsung     | Hitachi HD 
                                                      | 830 512GB    | 840 1TB     | 1TB 5400 RPM
----------------------------------------------------------------------------------------------------------------
dd if=/dev/sda3 of=/dev/null bs=1M count=2000         |              |             |
2097152000 bytes (2.1 GB) copied, 4.65606 s, 450 MB/s | 479MB/s      | 541MB/s     | 104 MB/s
                                                      |              |             |
hdparm -t /dev/sda3                                   |              |             |
/dev/sda3:                                            |              |             |
 1430 MB in  3.00 seconds =               476.12 MB/s | 463.45 MB/s  | 1112.81MB/s | 99.83 MB/s
                                                      |              |             |
Unencrypted ext4 block read:                          |              |             |
reset_cache; dd if=testcopy of=/dev/null bs=1M        |              |             |
2146631680 bytes (2.1 GB) copied, 4.21942 s, 509 MB/s |              | 458MB/s     | 105 MB/s
                                                      |              |             |
Unencrypted btrfs block read:                         |              |             |
reset_cache; dd if=testcopy of=/dev/null bs=1M        |              |             |
2146631680 bytes (2.1 GB) copied, 4.31774 s, 497 MB/s | 495 MB/s     | 542MB/s     | 90.3 MB/s
                                                      |              |             |
Encrypted btrfs block read:                           |              |             |
dd if=w2k-s001.vmdk of=/dev/null bs=1M     kernel 3.5 | kernel 3.5   | kernel 3.11 | kernel 3.5
2146631680 bytes (2.1 GB) copied, 6.51863 s, 329 MB/s | 253 MB/sec   | 533 MB/sec  | 69.1 MB/s

Block writes on Vertex 4 and (vs spinning hard drive)

I didn't benchmark write speed on the Samsung 830 because I couldn't get random reads to be fast, so I didn't care about writes.

Summary:

OCZ Vertex 4 512GB:                           | Samsung EVO  | Hitachi 1TB 
                                              | 840 1TBM     | 5400 RPM
---------------------------------------------------------------------------
Raw device write (write to /dev/sdxx bs=1M)   |  kernel 3.11 |
(2.1 GB) copied, 9.35569 s, 229 MB/s          |  430 MB/s    |  90.9 MB/s
                                              |              |
File write on unencrypted ext4:               |  kernel 3.11 |
(2.1 GB) copied, 11.3984 s, 188 MB/s          |  495 MB/s    |  92.0 MB/s
                                              |              |
File write on unencrypted btrfs:              |  kernel 3.11 |
(2.1 GB) copied, 8.58974 s, 250 MB/s          |  413 MB/s    |  130 MB/s
                                              |              |
File write through encryption layer on btrfs  |  kernel 3.11 |
(2.1 GB) copied, 16.4673 s, 130 MB/s          |  341 MB/s    |  95.6 MB/s

SSD winner and conclusions

The OCZ Vertex 4 512GB won by far obviously. The price is competitive, the speed beats pretty much everything out there, and the 5 year warranty shows that they mean business (most only offer 1, 2, or sometimes 3 years). 5 years is a record in this field.
Well, that was then, turns out OCZ was more confident than good, their drives did lock up, they made bad tradeoffs on other drives as explained by Luke on http://lkcl.net/reports/ssd_analysis.html, and they are now going bankrupt as of Dec 2013.
After about a year of use, I confirmed that the OCZ drive is just unstable with linux/dmcrypt/btrfs on my laptop. I'm not sure what part causes it to hang and require a power cycle every other day or so after a few months of use, but that was quite annoying.

I'm now hopeful that the Samsung EVO 840 will be my new "good drive" for a long longer :)

It sucks that it took me so long to find a good drive, and so many backup/restore cycles, but I think I got it now. Wish me luck! :)

"How To Succeed Without Really Trying" is an old musical that was performed at Foothill College. It was actually quite enjoyable for an old musical from a work area that is quite different from today's work culture, and the performers were quite good too.

I need to remember that Foothill does perform good plays.

a few other people were outside to do their own viewing

We got there 15mn before sunset (i.e barely in time to get a few pictures), and went to attend the history talk about James Lick. His story is actually quite interesting, you can read up on it here. Because Jennifer was still on crutches, they thought it'd be best that we stayed in the room with the great lick 36 inch refractor. It was actually quite cool to see it operated, that also meant that we did not get to see the science talk that was being given at the same time :(

By missing the science talk, we got to see the refractor being setup, and it's so long that the entire floor is raised and lowered so that the operator can be at the right height. It's pretty cool :)

After looking at the constellation they finally managed to focus on after a while, we went to see the Nickel Telescope, which is a 40 inch reflecting telescope which was actually made out of spare parts.

A few random slides they were showing on screens:

The drive home was also fun :)

The other interesting thing is that it weighs 900kg, or almost the weight of my miata, and that was the largest weight they had the technology to send to Mars, without it crashing on impact. The last rovers were 9 times lighter and were dropped in giant airbags. This was too heavy for airbags and had to be dropped with 2 different parachutes for different speeds, and then slowed down with trusters and a platform that lowered the rover down with cables on the ground and flew off. It was a very complicated list of things that had to go just right.
I personally thought "no way, those guys are crazy", and they indeed called the landing "the 7 minutes of terror", but it not only went perfectly, the rover was also able to send pictures right after touch down, something that they weren't sure would work at all that night, due to radio relay line of sight issues.

It was flawless, great job folks!

Nasa Moffett designed and tested the chute in the wind tunnel

And then we "watched" a rendering of the landing from telemetry that was received (14mn late):

that's the flying platform lowering the rover to the ground with cables