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Re: Schrödinger's hash

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On 5/22/26 17:16, nwe wrote:
> On 5/22/26 6:25 PM, David Christensen wrote:
> 
>> I am still trying to understand the smartctl(8) "SMART Attributes Data 
>> Structure".  The RAW_VALUE seems to be a binary bit field (?) 
> 
> same here
> 
> some makes/models of hardware seem to produce a greater quantity of 
> comprehensible smart data
> 
> I run like
> # smartctl -x /dev/sdf
> returns additional data.
> 
> 
>> Twelve disks gives you many choices for how to layout the pool and 
>> trade-off redundancy vs. capacity vs. performance.  Is the data 
>> balanced across disks?  Does the machine have enough memory?  Is the 
>> ARC working well?
> 
> It has 256GB RAM.
> 
> My desktop pc currently has only 1Gb networking ever since I replaced my 
> fiber optic card with a gpu in the lone PCIe slot. During the time I had 
> 10g networking direct from server to workstation, I recall easily 
> saturating the network. Amazing speed, but I needed the gpu more. 10g 
> networking is faster than the cheap SSDs in most of my PCs.


12 HDD raidz3 already exceeds 10 Gbps for sequential I/O.


256 GB of memory could be enough to fit your entire workload within the 
ARC, so random I/O may have also saturated 10 Gbps.  If your processor 
memory bus has enough channels, your NIC has enough PCIe lanes, and your 
workload does not require synchronous writes (or you tune ZFS to fake 
it), a suitable workstation or backup server could saturate 25, 50, 100 
Gbps single/ dual/ quad Ethernet.  SFPx switches are expensive, so I 
have considered dual SFPx cards in my workstation, primary server, and 
backup server; connected in a ring.


If you have a USB 3.x A or C port, various manufacturers make 2.5, 5, 
and 10 GbE (copper RJ-45) Ethernet adapters.  If you have a Thunderbolt 
3, 4, or 5 port, a few make 10 and 25 Gbps SFPx fiber single and dual 
Ethernet adapters.  Be sure to verify Debian and Linux driver support 
with the manufacturer before purchasing:

https://www.amazon.com/s?k=thunderbolt+sfp+ethernet

https://www.sonnettech.com/product/twin25g/overview.html


I have been using Intel SSD 520 Series 2.5" SATA III drives for many 
years.  They are an enterprise grade product that were put in various 
desktops, laptops, and netbooks ~14 years ago.  Resellers harvest and 
resell them on eBay.  The 60 GB model works well for Linux and FreeBSD 
system drives.  The 180 GB model has the best performance 
specifications, and works well for Windows system drives and ZFS 
accelerators (at my 6 TB scale).  Prices for used smaller drives can 
still be reasonable in spite of the AI bubble.


All that said, when your workload goes outside the ARC or the HDD 
caches, HDD latency will become the bottleneck.  SATA/SAS 6 or 12 Gbps 
SSD accelerators chosen to match the workload could help.  NVMe PCIe 
would be even better.  Optane would be best:

https://goughlui.com/2024/07/28/tech-flashback-intel-optane-3d-xpoint-memory/


How do you back up a 36 TB pool?


David

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Schrödinger's hash Charles Curley <charlescurley@charlescurley.com> - 2026-05-22 18:00 +0200
  Re: Schrödinger's hash Andrew Latham <lathama@gmail.com> - 2026-05-22 18:10 +0200
    Re: Schrödinger's hash Charles Curley <charlescurley@charlescurley.com> - 2026-05-22 18:20 +0200
      Re: Schrödinger's hash Andrew Latham <lathama@gmail.com> - 2026-05-22 18:30 +0200
        Re: Schrödinger's hash Charles Curley <charlescurley@charlescurley.com> - 2026-05-22 19:00 +0200
    bad RAM (Was: Schrödinger's hash) nwe <nwe@gitcoding.net> - 2026-05-22 19:40 +0200
      Re: bad RAM (Was: Schrödinger's hash) Charles Curley <charlescurley@charlescurley.com> - 2026-05-22 22:10 +0200
        Re: bad RAM (Was: Schrödinger's hash) nwe <nwe@gitcoding.net> - 2026-05-22 22:30 +0200
          Re: bad RAM (Was: Schrödinger's hash) Charles Curley <charlescurley@charlescurley.com> - 2026-05-22 23:10 +0200
            Re: bad RAM (Was: Schrödinger's hash) nwe <nwe@gitcoding.net> - 2026-05-22 23:30 +0200
          Re: bad RAM (Was: Schrödinger's hash) David Christensen <dpchrist@holgerdanske.com> - 2026-05-23 02:00 +0200
            Re: bad RAM (Was: Schrödinger's  hash) Andy Smith <andy@strugglers.net> - 2026-05-25 13:20 +0200
              Re: bad RAM (Was: Schrödinger's hash) David Christensen <dpchrist@holgerdanske.com> - 2026-05-25 23:20 +0200
          Re: bad RAM Anssi Saari <anssi.saari@debian-user.mail.kapsi.fi> - 2026-05-25 11:50 +0200
  Re: Schrödinger's hash The Wanderer <wanderer@fastmail.fm> - 2026-05-22 18:20 +0200
    Re: Schrödinger's hash Charles Curley <charlescurley@charlescurley.com> - 2026-05-22 19:10 +0200
  Re: Schrödinger's hash David Christensen <dpchrist@holgerdanske.com> - 2026-05-22 20:10 +0200
  Re: Schrödinger's hash Van Snyder <van.snyder@sbcglobal.net> - 2026-05-22 20:40 +0200
    Re: Schrödinger's hash nwe <nwe@gitcoding.net> - 2026-05-22 21:50 +0200
      Re: Schrödinger's hash David Christensen <dpchrist@holgerdanske.com> - 2026-05-23 01:30 +0200
        Re: Schrödinger's hash Van Snyder <van.snyder@sbcglobal.net> - 2026-05-23 01:40 +0200
        Re: Schrödinger's hash nwe <nwe@gitcoding.net> - 2026-05-23 02:20 +0200
          Re: Schrödinger's hash David Christensen <dpchrist@holgerdanske.com> - 2026-05-23 07:50 +0200
            Home server (Was: Re: Schrödinger's hash) nwe <nwe@gitcoding.net> - 2026-05-23 17:00 +0200
              Re: Home server (Was: Re: Schrödinger's hash) David Christensen <dpchrist@holgerdanske.com> - 2026-05-24 04:30 +0200

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