Re: SSD based sw RAID: is ERC/TLER really important?

[pg@raid.list.sabi.co.UK (Peter Grandi)]

[...]

> I must not be the only one ignoring you, causing you to use
> multiple subdomains.

It seems sad that my changing address occasionally when they get
spammed as they get "harvested" may tickle someone's foolish
arrogance of thinking themselves so important that it is done
just to get their worthless attention.
http://www.sabi.co.uk/blog/0705may.html?070527c#070527c

Unfortunately in some cases my technical comments therefore get
replies without any technical content. As to this though:

> without going in detail about all other possible cases.

There are indeed many twists and turns and "legacy" situations,
as in several places timeouts and retries are hardcoded, and
IIRC the "default" for retries is 5. But I have spent a bit of
time looking at some of the weirdness and it turns out that
nowadays the 'sd' module defines a 'max_retries' setting in the
device attributes (rather than a module parameter as in
'nvme_core'):

  https://elixir.bootlin.com/linux/latest/source/drivers/scsi/sd.c#L598

It is only available from 5.10 and would be for example at:

  /sys/class/scsi_disk/0:0:0:0/max_retries

I have also noticed that XFS bizarrely has its own layer of
recovery on top of that of the Linux IO subsystems and of the
device itself:

  https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html/managing_file_systems/configuring-xfs-error-behavior_managing-file-systems
  https://elixir.bootlin.com/linux/v5.13.5/source/fs/xfs/xfs_buf.c#L1264