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Which SoC boards have ECC ram? ECC ram is essential for any reliable data storage system. Disks have built-in error correcting codes, and RAID can detect errors

by mrob 1y ago

Which SoC boards have ECC ram? ECC ram is essential for any reliable data storage system. Disks have built-in error correcting codes, and RAID can detect errors, but none of this helps if the data is corrupted in RAM before it ever reaches the disk.

reactordev 1y ago
The RPI CM5…
- deleted 1y ago
  [deleted]
- mrob 1y ago
  The specs claim "ECC" [0], but give no further details. ejolson on the Raspberry Pi forums [1] thinks it is on-die ECC, not traditional ECC, which would mean transfers between the RAM and the memory controller are not protected and there are no means of monitoring errors or triggering a kernel panic if there's an uncorrectable error. Some discussion on Reddit [2] also suggests it's on-die ECC. If this is true, it's better than nothing but still not a replacement for a NAS with traditional ECC RAM. [0] https://www.raspberrypi.com/products/compute-module-5/?variant=cm5-104032 https://www.raspberrypi.com/products/compute-module-5/?varia... [1] https://forums.raspberrypi.com/viewtopic.php?p=2296449#p2296449 https://forums.raspberrypi.com/viewtopic.php?p=2296449#p2296... [2] https://old.reddit.com/r/raspberry_pi/comments/1irryax/raspberry_pi_cm5_ecc_memory_details/ https://old.reddit.com/r/raspberry_pi/comments/1irryax/raspb...
  - reactordev 1y ago
    The chip is the memory controller… Yes it’s on-die. Yes it has error reporting. Don’t spread fud. There isn’t a dedicated chip because there doesn’t need to be. Broadcom BCM2712
    - mrob 1y ago
      In that case I incorrectly thought (like the other forum posters) it was like DDR5 on-die ECC. What you describe is better than DD5 on-die ECC. Is this error reporting supported by Linux? Is there some way I can do fault injection (e.g. undervolting the RAM) to check it's working?
j45 1y ago
ECC is very helpful. Having used both, I can't help but notice how NAS' routinely run just fine without it.
- mrob 1y ago
  >NAS' routinely run just fine without it. How do you verify your data to confirm that?
  - geerlingguy 1y ago
    ZFS helps, and many people are okay with the risk of a cosmic ray causing a bit flip while data is in flight once in a blue moon. I currently manage four NASes (two primary, two backup replicas). Only one has ECC RAM. And I'm okay with my setup. ECC is great to have, but it is oversold by some as being absolutely required for all storage devices, IMO.
    - turnsout 1y ago
      For truly important files (photos), I’ll take the slight added expense of ECC for a little more peace of mind that old photos aren’t being gradually degraded with every resilver or scrub.
      - j45 1y ago
        Good point about ZFS. Having more than one copy helps too. ECC is great when possible.
  - j45 1y ago
    My first thought is the same way everyone's laptops and desktops and cellphones without ECC data do? I'll share any more that come to mind.
  - j45 1y ago
    Multiple backups. How many files have you personally seen gone corrupt on non-ecc? ECC originated first out of server grade servers. Self-hosting rarely hits that level of demand.

by mrob 1y ago

reactordev 1y ago

The RPI CM5…

deleted 1y ago
[deleted]
mrob 1y ago
The specs claim "ECC" [0], but give no further details. ejolson on the Raspberry Pi forums [1] thinks it is on-die ECC, not traditional ECC, which would mean transfers between the RAM and the memory controller are not protected and there are no means of monitoring errors or triggering a kernel panic if there's an uncorrectable error. Some discussion on Reddit [2] also suggests it's on-die ECC. If this is true, it's better than nothing but still not a replacement for a NAS with traditional ECC RAM. [0] https://www.raspberrypi.com/products/compute-module-5/?variant=cm5-104032 https://www.raspberrypi.com/products/compute-module-5/?varia... [1] https://forums.raspberrypi.com/viewtopic.php?p=2296449#p2296449 https://forums.raspberrypi.com/viewtopic.php?p=2296449#p2296... [2] https://old.reddit.com/r/raspberry_pi/comments/1irryax/raspberry_pi_cm5_ecc_memory_details/ https://old.reddit.com/r/raspberry_pi/comments/1irryax/raspb...
- reactordev 1y ago
  The chip is the memory controller… Yes it’s on-die. Yes it has error reporting. Don’t spread fud. There isn’t a dedicated chip because there doesn’t need to be. Broadcom BCM2712
  - mrob 1y ago
    In that case I incorrectly thought (like the other forum posters) it was like DDR5 on-die ECC. What you describe is better than DD5 on-die ECC. Is this error reporting supported by Linux? Is there some way I can do fault injection (e.g. undervolting the RAM) to check it's working?

j45 1y ago

ECC is very helpful. Having used both, I can't help but notice how NAS' routinely run just fine without it.

mrob 1y ago
>NAS' routinely run just fine without it. How do you verify your data to confirm that?
- geerlingguy 1y ago
  ZFS helps, and many people are okay with the risk of a cosmic ray causing a bit flip while data is in flight once in a blue moon. I currently manage four NASes (two primary, two backup replicas). Only one has ECC RAM. And I'm okay with my setup. ECC is great to have, but it is oversold by some as being absolutely required for all storage devices, IMO.
  - turnsout 1y ago
    For truly important files (photos), I’ll take the slight added expense of ECC for a little more peace of mind that old photos aren’t being gradually degraded with every resilver or scrub.
    - j45 1y ago
      Good point about ZFS. Having more than one copy helps too. ECC is great when possible.
- j45 1y ago
  My first thought is the same way everyone's laptops and desktops and cellphones without ECC data do? I'll share any more that come to mind.
- j45 1y ago
  Multiple backups. How many files have you personally seen gone corrupt on non-ecc? ECC originated first out of server grade servers. Self-hosting rarely hits that level of demand.