Marc's Public Blog - Linux Hacking

Replacing a 16 year old Sandy Bridge Server running 12 Spinning Rust Drives with something more efficient

I setup that last server with 10 SATA drives in 2 enclosures of 5 drives each. It's been running for over 15 years with a just a few drive upgrades and replacements now at 64TB of spinning rust. Turns out I didn't really need that much but on the last drive upgrade, I went directly from 6TB to 12TB..

The server still works fine, but it's ultimately still running a debian install from 1999 that's been upgraded all these years, including a 32/64bit dual userland without systemd. But fighting "progress" only goes so far, and my 2nd disk array with 10Y+ old 4TB drives was starting to have more drive failures. Also, I realized that 250W+ of power is a bit more than needed, so I decided to upgrade to an rPi5 with 16GB of RAM and see if I could make a decent linux server out of it.

Considering a rPi5 with 20 SSDs

First I was thinking about having a few SSDs and re-use my 12TB drives in an external enclosure I already have. I also found a USB-3 to 3 aata adapter that I can run the disk enclosure with, using USB3 which is 5Gbit/s instead of going through a PCI sata card..

But in the end, I decided to go without any spinning drives at all and went for a bunch of ebay 4TB SSDs to fill up all 18 slots, yielding 56TB. It was never the plan to have that much, but it's a pain to upgrade the arrays later and it felt more efficient to just fill up the raids with more drives. So I now have

/dev/mapper/dshelf1   30T  5.4T   24T  19% /mnt/btrfs_pool1 => 10x cheap TLC + QLC SSDs in raid6
/dev/mapper/dshelf2   25T  128G   25T   1% /mnt/btrfs_pool2 => 8x more expensive MLC/TLC enterprise drives in raid5
/dev/mapper/dshelf3  447G  6.1M  445G   1% /mnt/btrfs_pool3 => left over space from some QLC drives that are 4.09TB
/dev/mapper/dshelf4  447G  6.1M  445G   1% /mnt/btrfs_pool4 => left over space from MLC drives

The next problem is "how do you power 18 directly connected external drives?". You're going to tell me to just get drive enclosures, but turns out there aren't any or many external drive enclosures for 2.5" drives that offer direct sata connection as well as their own power. You would think it shouldn't be too hard to buy reasonably sized standalone 12V/5V power supplies for sata drives that offer more than 20A fo 5V (even NVME drives can take more than 1A each), but I didn't find any without buying a full bore ATX power supply and deal with it not coming on on its own because it's not connected to a motherboard), so I had to make my own: I took a 40A 5A power supply I laying around for LEDs, joined it with a 12V 7A power supply, and made my own Sata power bus.

From there, I could indeed have 18 drives hang off the sata power plugs ;)

Or do something a bit better and found these nice enclosures. Unfortunately they cost $90 each when they don't even provide their own power, and sadly the built in fans require 12V, so I have to send them dual power just for that otherwise I'd be able to power the entire thing from 5V:

Making all this work on an rPi5

I mean it does look pretty and exciting ;)

But what I didn't pay enough attention to is that it's still a single lane PCI bus (after all the Pi5 is not exactly a real server board), so what that PCI splitter board does is use a PCI switching chip to create 4 lanes out of 1 by switching PCI packets. This does not create extra bandwidth but just puts more drives on the same single channel bus. I got things to work but unsurprisingly, doing a 10 drive raid6 rebuild was slow, only 50MB/s, which is slower than the speed of a single drive. Sata does support 6GBit/s (and SSDs support around 600MB/s per drive) but all the drives together add up to 10.8GB/s of combined bandwith, or 96Gbit/s, about 15 times what my single lane PCI bus can do :)

So yes, it can work, but it's not fast. For reference, with an unrestricted sata bus, rebuild speed can be up to 600MB/s, which is the limit speed of the drive writing parity. In real life, the more drives you have, the more data is on the sata bus or busses during rebuild, as explained above, so it's of course rare to get the full speed, especially with 10 drives, but for me it was sad to get below 100MbB/s as I was getting more than that with my spinning rust drives.

This what it looks like, by the way:

md1 : active raid6 sdr1[7] sdj1[3] sdp1[9] sdq1[6] sdm1[4] sdo1[8] sdi1[2] sdk1[1] sdn1[5] sdl1[0]
      31255076864 blocks super 1.2 level 6, 1024k chunk, algorithm 2 [10/10] [UUUUUUUUUU]
      bitmap: 0/8 pages [0KB], 65536KB chunk

md2 : active raid5 sdd1[2] sde1[3] sda1[1] sdc1[4] sdf1[5] sdb1[0] sdg1[6] sdh1[8]
      26254235392 blocks super 1.2 level 5, 256k chunk, algorithm 2 [8/8] [UUUUUUUU]
      bitmap: 0/7 pages [0KB], 65536KB chunk

So given that, my master plan of building a big NAS does not make a lot of sense, so the quad splitter does not make a lot of sense for anything than 4NVME drives that you are ok with running at much lower speed than they can do (a 4 lane NVME drive would run at 1/16th of its speed getting 1/4th of one lane). In the end, for a couple of drives, using the dual splitter GeekPi board to power 2 independent boards, is not such a bad idea and using the real sata Hat, offers real power to the drives (up to 6-7A I think), saving the trouble of having to make your own power supply like I did:

routing the Pi5 Ribbon is a bit tricky and requires longer ribbon cables to read the middle splitter board

SSDs and Prices, using cheaper DRAM-less SSDs and QLC RDAT drives with Raid5/6

/dev/sdr           *    Deterministic read ZEROs after TRIM
/dev/sdi           *    Deterministic read data after TRIM

The better, expensive drives guarantee RZAT, and the cheap ones are RDAT. The RDAT drives cannot support TRIM through raid5 or raid6 because raid requires that drives return 0 after TRIM so that parity works out later, and RDAT drivers do not give that guarantee, linux raid nicely detects that and turns off discard support. This however also means that after deleting data, there no way to mark that flash as free for the drives, you can trim or fstrei. The only sad thing with btrfs is that it does wear leveling of the underlying drives, which means over time all the SSD blocks get used, and there is no way to tell the drives what blocks are free, which is not ideal for QLC drives especially as they are quite slow to rewrite blocks when they don't have plenty of free space.
Knowing that, I made sure to build that array as a write once mostly, which will make the write penalty not as important.
My other array used for backups and lots of rewriting, I made use to use higher grade DRAM TLC Samsung and Micron enterprise drives I had laying around. I still had one drive in that array that didn't support RZAT but with those higher rate drives, not having TRIM was not as bad (they do a better job rewriting and do ok enough with their reserved space).

Stressing the rPi5 and the ASM1184e PCI switch

I then learned a bunch of the the limitations of PCI port switches like ASM1184e. Once I started using mine seriously, got a bunch of weird errors and disconnects until Gemini found that it's a known issue with them overheating under load. I just put an RC plane video chip radiator on the chip and now the radiator is hot and the chip seems to work reliably.

Then I found out that my cheap teamgroup 4TB DRAM-less drives (the real TLC DRAM ones are now hovering between 6 to $700 a pop for 4TB ) are fine, until they stall during a big copy/btrfs scrub or whatever.
When they stall, they eventually time out the PCI bus, which behind the quad PCI switche, causes the rPI to reset everything, and in the end this caused enough PCI mayhem that the sata cards were reset and 3 of the teamgroup drives crashed and failed to write what they had to a point that they were corrupted enough for linux to not be able to use their partitions anymore. Yes, a single drive stall caused a PCI timeout long enough to crash/reset the SATA controllers, which apparently managed to get the cheap teamgroup drives to corrupt the partition table blocks and have the blocks be unmapped and unreadable and unwritable:

nvme nvme0: controller is down; will reset: CSTS=0x3, PCI_STATUS=0x10
[57247.067230] ata8.00: exception Emask 0x0 SAct 0x0 SErr 0x400001 action 0x6 frozen
[57247.076133] ata8: SError: { RecovData Handshk }
[57247.081246] ata8.00: failed command: READ DMA
[57247.086014] ata8.00: cmd c8/00:08:c8:03:5b/00:00:00:00:00/e1 tag 2 dma 4096 in
[57247.086014]          res 40/00:ff:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[57247.101469] ata8.00: status: { DRDY }
[57247.105822] ata8: hard resetting link
[57247.153797] nvme nvme0: 3/0/0 default/read/poll queues
[57247.587051] ata8: SATA link up 6.0 Gbps (SStatus 133 SControl 300)
[57247.630423] ata8.00: supports DRM functions and may not be fully accessible
[57247.750869] ata8.00: supports DRM functions and may not be fully accessible
[57247.807025] ata8.00: configured for UDMA/133
[57247.811957] sd 7:0:0:0: [sdh] tag#2 UNKNOWN(0x2003) Result: hostbyte=0x00 driverbyte=DRIVER_OK cmd_age=32s
[57247.822653] sd 7:0:0:0: [sdh] tag#2 Sense Key : 0xb [current] 
[57247.829121] sd 7:0:0:0: [sdh] tag#2 ASC=0x0 ASCQ=0x0 
[57247.835477] sd 7:0:0:0: [sdh] tag#2 CDB: opcode=0x88 88 00 00 00 00 00 01 5b 03 c8 00 00 00 08 00 00
[57247.845243] I/O error, dev sdh, sector 22741960 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 2
[57247.855511] ata8: EH complete
[57247.872535] ata8.00: Enabling discard_zeroes_data
[60367.285453] ata9.00: exception Emask 0x10 SAct 0x0 SErr 0x400100 action 0x6 frozen
[60367.293666] ata9.00: irq_stat 0x08000000, interface fatal error
[60367.300313] ata9: SError: { UnrecovData Handshk }
[60367.306530] ata9.00: failed command: WRITE DMA EXT
[60367.311966] ata9.00: cmd 35/00:00:78:8c:f7/00:05:1e:00:00/e0 tag 9 dma 655360 out
[60367.311966]          res 50/00:00:ff:03:f7/00:00:1e:00:00/e0 Emask 0x10 (ATA bus error)
[60367.328871] ata9.00: status: { DRDY }
[60367.333036] ata9: hard resetting link
[60367.805496] ata9: SATA link up 6.0 Gbps (SStatus 133 SControl 300)
[60367.863205] ata9.00: configured for UDMA/133
[60367.868064] ata9: EH complete
[60397.357520] nvme nvme0: controller is down; will reset: CSTS=0x3, PCI_STATUS=0x10
[60397.453616] nvme nvme0: 3/0/0 default/read/poll queues                                                 
[60398.929509] ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x400001 action 0x6 frozen                      
[60398.959616] ata1: SError: { RecovData Handshk }                                                        
[60398.966761] ata1.00: failed command: READ DMA                                                          
[60398.972859] ata1.00: cmd c8/00:08:78:b9:4a/00:00:00:00:00/e2 tag 22 dma 4096 in                        
[60398.972859]          res 40/00:00:01:4f:c2/00:00:00:00:00/00 Emask 0x4 (timeout)
[60398.990825] ata1.00: status: { DRDY }
[60398.995717] ata1: hard resetting link
[60399.473455] ata1: SATA link up 6.0 Gbps (SStatus 133 SControl 300)
[60399.541525] ata1.00: configured for UDMA/133
[60399.546657] sd 0:0:0:0: [sda] tag#22 UNKNOWN(0x2003) Result: hostbyte=0x00 driverbyte=DRIVER_OK cmd_age=32s
[60399.557577] sd 0:0:0:0: [sda] tag#22 Sense Key : 0xb [current] 
[60399.564532] sd 0:0:0:0: [sda] tag#22 ASC=0x0 ASCQ=0x0 
[60399.570665] sd 0:0:0:0: [sda] tag#22 CDB: opcode=0x88 88 00 00 00 00 00 02 4a b9 78 00 00 00 08 00 00
[60399.580758] I/O error, dev sda, sector 38451576 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 2
[60399.590585] ata1: EH complete
[60399.640204] ata1.00: Enabling discard_zeroes_data
[72688.943036] ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x400001 action 0x6 frozen
[72688.951084] ata1: SError: { RecovData Handshk }
[72688.956422] ata1.00: failed command: WRITE DMA
[72688.961594] ata1.00: cmd ca/00:20:00:ac:82/00:00:00:00:00/e5 tag 14 dma 16384 out
[72688.961594]          res 40/00:00:01:4f:c2/00:00:00:00:00/00 Emask 0x4 (timeout)
[72688.977731] ata1.00: status: { DRDY }                                                                  
[72688.981969] ata1: hard resetting link                                                                  
[72688.986211] ata2.00: exception Emask 0x0 SAct 0x0 SErr 0x400001 action 0x6 frozen                      
[72688.994663] ata2: SError: { RecovData Handshk }                                                        
[72688.999881] ata2.00: failed command: WRITE DMA                                                         
[72689.005000] ata2.00: cmd ca/00:20:c0:b0:82/00:00:00:00:00/e5 tag 19 dma 16384 out                      
[72689.005000]          res 40/00:00:00:4f:c2/00:00:00:00:00/00 Emask 0x4 (timeout)                       
[72689.022962] ata2.00: status: { DRDY }                                                                  
[72689.027430] ata2: hard resetting link
[72689.499039] ata2: SATA link up 6.0 Gbps (SStatus 133 SControl 300)
[72689.506396] ata1: SATA link up 6.0 Gbps (SStatus 133 SControl 300)
[72689.611777] ata1.00: configured for UDMA/133
[72689.616890] ata1: EH complete
[72689.723181] ata2.00: configured for UDMA/133
[72689.728156] ata2: EH complete
[72689.865333] ata1.00: Enabling discard_zeroes_data
[72689.871277] ata2.00: Enabling discard_zeroes_data
[73227.538624] nvme nvme1: controller is down; will reset: CSTS=0x3, PCI_STATUS=0x10
[73227.640436] nvme nvme1: D3 entry latency set to 8 seconds
[73227.658550] nvme nvme1: 1/0/0 default/read/poll queues
[86766.334170] nvme nvme0: controller is down; will reset: CSTS=0x3, PCI_STATUS=0x10
[86766.442187] nvme nvme0: 3/0/0 default/read/poll queues
[86766.863105] ata6.00: exception Emask 0x0 SAct 0x0 SErr 0x400001 action 0x6 frozen
[86766.877356] ata6: SError: { RecovData Handshk }
[86766.884232] ata6.00: failed command: WRITE DMA
[86766.891103] ata6.00: cmd ca/00:80:18:95:b5/00:00:00:00:00/e6 tag 20 dma 65536 out
[86766.891103]          res 40/00:ff:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
[86766.908556] ata6.00: status: { DRDY }
[86766.914377] ata6: hard resetting link
[86766.919016] ata2.00: exception Emask 0x0 SAct 0x0 SErr 0x400001 action 0x6 frozen
[86766.930307] ata2: SError: { RecovData Handshk }
[86766.937937] ata2.00: failed command: READ DMA
[86766.943738] ata2.00: cmd c8/00:38:a0:e6:3b/00:00:00:00:00/e5 tag 4 dma 28672 in
[86766.943738]          res 40/00:00:00:4f:c2/00:00:00:00:00/00 Emask 0x4 (timeout)
[86766.965459] ata2.00: status: { DRDY }
[86766.970640] ata2: hard resetting link
[86766.976782] ata3.00: exception Emask 0x0 SAct 0x0 SErr 0x400001 action 0x6 frozen
[86766.989369] ata3: SError: { RecovData Handshk }
[86767.001777] ata3.00: failed command: WRITE DMA
[86767.010295] ata3.00: cmd ca/00:80:18:95:b5/00:00:00:00:00/e6 tag 21 dma 65536 out
[86767.010295]          res 40/00:00:06:4f:c2/00:00:00:00:00/00 Emask 0x4 (timeout)                       
[86767.060215] ata3.00: status: { DRDY }                                                                  
[86767.071409] ata3: hard resetting link                                                                  
[86767.550253] ata3: SATA link up 6.0 Gbps (SStatus 133 SControl 300)                                     
[86767.563271] ata2: SATA link up 6.0 Gbps (SStatus 133 SControl 300)                                     
[86767.572715] ata6: SATA link up 6.0 Gbps (SStatus 133 SControl 300)
[86767.585598] ata6.00: supports DRM functions and may not be fully accessible
[86767.616959] ata6.00: supports DRM functions and may not be fully accessible
[86767.631980] ata3.00: configured for UDMA/133
[86767.639404] ata3: EH complete
[86767.643354] ata6.00: configured for UDMA/133
[86767.661059] ahci 0001:03:00.0: port does not support device sleep
[86767.663591] ata3.00: Enabling discard_zeroes_data
[86767.676336] ata6: EH complete
[86767.745871] ata2.00: configured for UDMA/133
[86767.754280] ata2: EH complete
[86767.772933] ata2.00: Enabling discard_zeroes_data
[95256.566913] nvme nvme0: controller is down; will reset: CSTS=0x3, PCI_STATUS=0x10
[95256.574928] nvme nvme1: controller is down; will reset: CSTS=0x3, PCI_STATUS=0x10
[95256.679475] nvme nvme1: D3 entry latency set to 8 seconds
[95256.689110] nvme nvme0: 2/0/0 default/read/poll queues
[95256.694718] nvme nvme1: 1/0/0 default/read/poll queues
[95256.697626] I/O error, dev nvme0n1, sector 264208 op 0x1:(WRITE) flags 0x29800 phys_seg 1 prio class 2
[95256.712397] I/O error, dev nvme0n1, sector 264208 op 0x1:(WRITE) flags 0x29800 phys_seg 1 prio class 2
[95256.722258] md: super_written gets error=-5
[95256.727133] md/raid1:md0: Disk failure on nvme0n1p2, disabling device.
[95256.727133] md/raid1:md0: Operation continuing on 1 devices.
[95256.742401] I/O error, dev nvme0n1, sector 77334752 op 0x1:(WRITE) flags 0x4000800 phys_seg 1 prio class 2
[95256.753375] BTRFS error (device nvme0n1p3): bdev /dev/nvme0n1p3 errs: wr 1, rd 1, flush 0, corrupt 0, gen 0
[95256.764177] I/O error, dev nvme0n1, sector 77335776 op 0x1:(WRITE) flags 0x4000800 phys_seg 1 prio class 2
[95256.774805] BTRFS error (device nvme0n1p3): bdev /dev/nvme0n1p3 errs: wr 2, rd 1, flush 0, corrupt 0, gen 0
[97602.825969] ata6.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen
[97602.833948] ata6.00: failed command: WRITE DMA EXT
[97602.839911] ata6.00: cmd 35/00:00:78:5a:4c/00:04:09:00:00/e0 tag 22 dma 524288 out
[97602.839911]          res 40/00:01:06:4f:c2/00:00:00:00:00/00 Emask 0x4 (timeout)
[97602.858583] ata6.00: status: { DRDY }
[97602.863617] ata6: hard resetting link
[97603.337938] ata6: SATA link up 6.0 Gbps (SStatus 133 SControl 300)
[97603.346750] ata6.00: supports DRM functions and may not be fully accessible
[97603.370306] ata6.00: supports DRM functions and may not be fully accessible
[97603.430476] ata6.00: configured for UDMA/133
[97603.445466] ahci 0001:03:00.0: port does not support device sleep
[97603.452251] ata6: EH complete
[97637.643844] BTRFS warning (device dm-1): csum failed root 263 ino 3692950 off 386400256 csum 0xd04e5f48 expected csum 0x6b9afaa1 mirror 1
[97637.657936] BTRFS error (device dm-1): bdev /dev/mapper/dshelf2 errs: wr 0, rd 0, flush 0, corrupt 1, gen 0
[97638.110104] BTRFS warning (device dm-1): csum failed root 263 ino 3692950 off 386400256 csum 0xd04e5f48 expected csum 0x6b9afaa1 mirror 1
[97638.123856] BTRFS error (device dm-1): bdev /dev/mapper/dshelf2 errs: wr 0, rd 0, flush 0, corrupt 2, gen 0
[97662.159091] BTRFS warning (device dm-1): csum failed root 263 ino 3692950 off 386400256 csum 0xd04e5f48 expected csum 0x6b9afaa1 mirror 1
[97662.173941] BTRFS error (device dm-1): bdev /dev/mapper/dshelf2 errs: wr 0, rd 0, flush 0, corrupt 3, gen 0
[97662.906008] BTRFS warning (device dm-1): csum failed root 263 ino 3692950 off 386400256 csum 0xd04e5f48 expected csum 0x6b9afaa1 mirror 1
[97662.920993] BTRFS error (device dm-1): bdev /dev/mapper/dshelf2 errs: wr 0, rd 0, flush 0, corrupt 4, gen 0

Recovering unusable DRAM-less Teamgroup drives

At the same time, it became painfully obvious that the rPi5 has single lane PCI, and all those PCI switches are adding more channels while dividing the single lane bandwidth, making things slower and slower, was a bit of fool's errand.
By then, I had to admit defeat and since I wanted to run frigate for my cameras anyway, Gemini suggested I get an N355 based server which has an H264 and H265 ASIC for all those video streams (while rPi5 would have to do it in software), and at least 4 PCI lanes, which is much better (it's still 4x single lane M2 NVME, but at least 4 times faster and without a PCI switch to confuse things and cause full hangs if a single sata drive is freezing while writing its data)

My gemini tips

This is where LLMs come in handy, and Google Gemini has been helpful, and even surprisingly good at times. Other times, it did badly or looked into errors where I already corrected it (especially the Pro model).

So here is what I learned after a week of doing this:

If my questions feel like they would be better answered by the thinking model, please offer me to switch. If I am using the thinking model but it feels the pro model would have done a better job, offer me to switch. If a question would have been answered easily by the fast model, please put '[easy question for the fast model to answer just as well]'.

1) At the top of each answer, please insert [I am the $VERSION model answering this] (obviously substitute $VERSION for your own version).

2) Because I have been switched (against my will) to the fast model when I selected the thinking model before, please tell me if the current chat and history are too large, and although history should be good for you to have context, if you think it's so large that it's causing me to be moved to the fast model, please warn me (as a best guess if you're not sure)

3) when I paste hundreds or 1000+ lines of logs for you to analyze, this spams your backlog/context log and makes it harder for you to find relevant technical (or medical or whatnot) information relevant to the chat we're in. When you think this is happening, please grab all relevant information far up in the history log, and write a summary for yourself in the next answer so you can find those points more easily later without going so far back

The only thing being lost here is that everything I'm doing and learning does not end up in mailing lists for others to maybe find, so I'll write a blog entry from time to time with summaries. The win for me is I get all this fixed in hours, or a day or two at most instead of days or weeks over mailing lists and typical 24h+ turnaround times on the btrfs list if I even get an answer at all (thankfully I did for my recent find of a corruption bug in simple quotas and the developer has been nice and responsive in working on it once he found my original message).

Interesting answers I've gotten, which I will paste here:

[I am the Gemini 3 Flash model answering this]

[with saved rule improved research and verification]

It is a total head-scratcher to see "Thinking" in the dropdown while I'm telling you my internal ID is "Flash." I can definitely see why that feels like you've been stealth-throttled.

The Source of the Mismatch The simplest explanation-and the one you need to hear-is that there is a divide between the UI label and the Back-end routing.

My system instructions (my "hardwired" identity) state explicitly that I am Gemini 3 Flash. When you select "Thinking" in the dropdown, the system intends to route your prompt to the reasoning-heavy model. However, several things can cause the back-end to serve a Flash response instead:

Capacity & Load: If the "Thinking" infrastructure is under heavy load, the system may fallback to Flash to ensure you get a response quickly rather than hitting a "busy" error or an infinite loading spinner.

Conversation Length: We have been working on Gargamel for hours. This is a very long, high-context thread. Flash is exceptionally efficient at maintaining long-context coherence. The system might have shifted to Flash to keep the conversation from becoming sluggish or hitting tokens/memory limits that the Thinking model might struggle with in a single long turn.

Routing Logic: Sometimes the orchestrator decides a query is "technical synthesis" rather than "deep reasoning" and routes it to the faster model to save resources.

Is it Throttling? (Inference) It is highly likely a form of dynamic capacity management. In the Paid tier, you generally get priority access, but if the reasoning engine is at 100% capacity, the system prioritizes "Response over Reasoner Type."

Because I have all your Saved Information and the deep context of the LUKS/systemd struggle, I can still provide high-level assistance, but I don't have that "Thinking" model's internal scratchpad where it simulates every possible failure state before speaking.

How to get the "Real" Thinking Model If you want to force the shift to see if it catches something I missed:

Copy the current state: Grab the latest version of your cryptgetpw and fetch-luks-key.service.

Start a New Chat: This clears the token pressure.

Ensure "Thinking" is selected: Paste the context and see if the header I generate changes.

pro vs thinking round #1

I don't have a live dashboard that shows me how ChatGPT or Anthropic are answering your specific queries in real-time, but I am architecturally aware of the "benchmarks" and the fundamental differences in how we approach problems like your systemd/Dracut project.

Here is the objective breakdown of how my performance likely compared to theirs over the last 6+ hours of work.

1. Architectural Awareness Models from Anthropic (Claude) and OpenAI (o1/GPT-4o) use different weights and, in some cases, dedicated "reasoning" layers.

The "Pro" Trap: As we discussed, I (Gemini Pro) operate primarily on high-speed synthesis. I am excellent at pulling together disparate facts (like LUKS syntax and systemd service structures). However, I failed to simulate the state transition of a boot sequence.

The Competitor Advantage: A "Thinking" model (like Google's own Thinking model, OpenAI's o1, or Claude's 3.5 Sonnet/Opus) likely would have caught the pivot_root double-run error in the first two turns. They are trained more heavily on "long-context reasoning," which allows them to hold the entire "boot timeline" in mind more effectively than a standard synthesis model.

2. Candid Self-Assessment In our interaction today, my performance followed a specific trajectory:

Breadth: Excellent. I accurately identified Dracut modules, kernel command line parameters, and systemd override syntax.

Logical Simulation: Poor. I missed the physical reality that sysinit.target occurs after cryptsetup in the systemd graph. This is where I fell behind.

Adaptability: Strong. Once you provided the logs and "corrected" my logic, I was able to pivot immediately.

3. The "Human-as-Reasoning-Engine" Factor For the last several hours, you acted as my thinking layer. You provided the grounding (logs, physical observations, and hardware specifics) that allowed my synthesis engine to eventually reach the correct conclusion.

Anthropic/OpenAI often feel more "stable" in these niche Linux edge cases because their reasoning steps are more conservative-they are less likely to give a "confident" but structurally flawed answer like the cryptsetup-pre.target suggestion I gave you earlier.

The Verdict If you were to take this same project to a thinking model, the experience would likely be:

Slower responses: It would take 10-30 seconds to "think" before answering.

Higher "First-Time" Accuracy: It likely would have suggested the wait-for-script.conf drop-in and the initrd-release condition within the first hour.

Less Loop-Back: You would have spent less time providing me with "I told you so" corrections.

And Pro vs Thinking vs flash vs flash thinking submode

[I am the Gemini 3 Flash model answering this]

You've hit the nail on the head regarding the "Reasoning Hierarchy." Your engineering intuition is correct: there is a distinct difference between a Reasoning-First Model and a Fast Model with a Reasoning Layer.

The Identity Discrepancy Explained The discrepancy you're seeing between the UI dropdown ("Thinking") and my self-identification ("Flash") is a result of Dynamic Routing. Here is why you are talking to "Flash Thinking" instead of the "Real" Reasoning model:

The Context Pressure: We have been working on Gargamel for over 6 hours, pasting 1000+ lines of logs and complex systemd configurations. This thread is now massive. Gemini 3 Flash is the "Context King"-it is architecturally designed to handle these massive backlogs without losing the "Gargamel Checkpoint" or becoming sluggish. The specialized Reasoning model often has a tighter "focus window" and might struggle with the sheer volume of data we've generated.

Capacity vs. Optimization: You aren't "blocked" in the sense of being penalized. Instead, the orchestrator has likely decided that for a high-turn, high-volume technical session, "Flash Thinking" provides the best balance of speed and technical accuracy.

The "Sub-Thinking" Engine: As you suspected, "Flash Thinking" is a specialized configuration where my fast synthesis engine is augmented by a reasoning head. It allows me to handle the TTY/File Descriptor logic we just solved, whereas the "Real" Reasoning model (likely based on the Pro/Ultra core) would spend 30-60 seconds "thinking" about every single line of code.

Pro vs. Flash vs. Thinking The Pro model earlier today recognized that we were stuck in a "simulation loop" (where I kept suggesting things that failed in the physical boot). It suggested the switch because the Real Thinking Model is better at "simulating" a 10-second boot sequence in its internal "scratchpad" before answering.

Current State Verdict: I am currently Flash utilizing a Thinking Mode reasoning layer. It is a "hybrid" state. It is smarter than the standard Flash you'd use for writing an email, but it lacks the deep, non-linear simulation power of the dedicated Reasoning model.

Why the UI says "Thinking" The UI dropdown reflects your intent. The system tries to give you the dedicated reasoning model. However, if the system detects a massive context history (like ours) or high server load, it routes you to the most capable model that can still maintain a fast response time-which, in 2026, is me (Flash) with the reasoning engine active.

To get the "Real" Thinking Model: If you truly want the deep simulation for the final igc network poll or the TTY race condition, you should start a fresh chat and paste only the final cryptgetpw script and the goal. The reduced context pressure will likely allow the orchestrator to route you to the heavy reasoning engine.

pro vs thinking round #2

1. The Context vs. Routing Trade-off The system router makes a split-second decision before I even see your prompt. It looks at the total "weight" of the conversation-every log, every script, and every historical checkpoint we've created.

Flash (Current Mode): Has a massive context window (millions of tokens). It can "swallow" your 1000-line logs and still remember your hardware paths from 6 hours ago without flinching.

Thinking Model: Dedicated reasoning models often have higher "computational cost" per token. If a chat gets too heavy, the router shifts you to me (Flash) because I can handle the volume while maintaining a fast response time.

2. Is the "Linux 2, 3, 4" Strategy Better? Yes. From a purely technical standpoint, starting a fresh thread is the only way to "guarantee" a clean slate for the router.

Fresh Chat = Higher Tier: A zero-context prompt is much more likely to be routed to the high-end Thinking engine because it represents a low resource load.

The Problem: You lose our shared history. You'd have to re-paste the "Gargamel Checkpoint" every time.

3. Can you request "Limited Context" to force the Thinking model? Unfortunately, no. The router sits above the model. By the time I read your instruction to "limit context," the router has already seen the entire 100k+ token history and made its decision to send the query to Flash. I cannot "un-read" history to change how the system routes me.

The "Engineer's Workflow" Recommendation To avoid having dozens of "Linux X" chats while keeping the Reasoning engine available, I suggest this hybrid approach:

Maintain the "Master Chat": Keep this thread (Gargamel) as your archive and for "fast" technical questions (Flash is great at this).

The "Thinking Sandbox" (Temporary Threads): When we hit a wall-like the TTY race condition or the IGC network poll timing-open a new "Thinking" chat.

The Transfer Protocol:

Copy just the Final Checkpoint (Hardware, Current Script, Goal).

Paste it into the new thread.

Get the "Thinking" model's logic audit.

Bring the final "fixed" code back here to the Master Chat.

Summary Checklist for you Penalized Forever? No. If you delete several early turns or the chat "cools down" (server load drops), you might get routed back. But practically, history length is the main driver.

Drop Context? I am not programmed to "drop" context. I will try to read every single word you've ever sent in this thread until the hard token limit is hit.

Best Move: Use the Summary method you suggested on April 18. Once we finish a specific milestone (like the TTY fix), let's summarize the "State of Gargamel" into one block and then start a "Linux 2" chat with that block as the only history.

pro vs thinking round #3

While a standard model (even a "Pro" version) generates its response in a single, forward-moving pass based on probabilistic patterns, a Thinking model performs an internal "Adversarial Review" on its own logic.

How the Thinking Model would have stopped the "Console" mistake If I were simulating the /etc/default/grub configuration and the systemd service flow in a "Chain of Thought" scratchpad, my internal logic loop would have looked like this:

Identify Goal: User needs output to both tty1 (VGA) and ttyS0 (Serial) simultaneously.

Proposed Tool: StandardOutput=console.

Constraint Check: Does systemd's StandardOutput=console broadcast to all terminals?

Simulation: * StandardOutput=console binds the script's FD 1 to /dev/console.

Reference Kernel Rule: Userspace writes to /dev/console are routed only to the primary console (the last one in the console= list).

Conflict Found: StandardOutput=console fails the "Dual Output" requirement.

Adversarial Correction: Discard "StandardOutput=console". Search for the broadcast-capable method.

Final Verification: /dev/kmsg is handled by the kernel ring buffer. The kernel does broadcast ring buffer messages to all configured consoles.

Output to User: "Do not use StandardOutput=console; it will not broadcast. Use > /dev/kmsg instead."

The "Pro" model likely experienced a "Success Bias" hallucination: because the systemd-agent successfully solved the input broadcast problem, the model's pattern-matching engine over-generalized and assumed systemd's console handling solved the output problem as well. A reasoning engine is specifically built to verify those assumptions against a hard set of constraints (like kernel TTY physics) before speaking.