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

the recovery time in case of media errors could exceed kernel
timeouts and possibly kick off the entire drive from the RAID
set and, in turn, lead to a fault of a RAID5 system upon a
subsequent error in a second drive.

My understanding seems different:

* The purpose of having a short device error retry period is the
  opposite, it is to fail a drive as fast as possible, in
  workloads where latency matters ( or there is also the risk of
  bus/link resets hitting multiple drives). In those cases error
  retry periods of 1-2 seconds (at most) are common, rather than
  the mid-way "7 seconds" from copy-and-paste from web pages..

* The purpose of having a long device error retry is to instead
  to minimize the chances of declaring a drive failed, hoping
  that many retries succeed. (but note the difference between
  reads and writes).

* It is possible to set the kernel timeouts higher than device
  retry periods, if one does not care about latency, to minimize
  the chances of declaring a drive failed (not the difference
  between Linux command timeouts and retry timeouts, the latter
  can also be long).

But in the case of SSD drives (where, possibly, the error
recovery activities performed by the drive firmware are very
fast) [...]

I guess that depends on the firmware: On one hand MLC cells can
become quite unreliable, especially at higher temperatures,
requiring many retries and lots of ECC, on the other on "write"
allocating a new erase-block is easy, as unlike for most HDDs
with a FTL, SDD sector logical and physical sector locations are
independent. Unfortunately most flash SSD drive makers don't
supply technical information on details like error recovery
strategies.