Hello lists
I am wondering what kind of support I can get from linux for
"inexpensive" (SATA over SAS HBA in my case) disks on RAID ...
Inexpensive non-raid-edition disks haven't got settable ERC timeout
(scterc) and can take very long time to respond in case of unreadable sector
However I see an /dev/sdX/device/timeout tunable
Supposing that I accept one disk being dropped from the array at the
first unreadable sector, can I set that tunable low such as 10sec and
live happy?
Unfortunately I have read that the expiration of the SCSI timeout can
trigger a "Host" reset in case the drive does not respond to a reset message
https://access.redhat.com/knowledge/docs/en-US/Red_Hat_Enterprise_Linux/5/html/Online_Storage_Reconfiguration_Guide/task_controlling-scsi-command-timer-onlining-devices.html
would that drop all my drives from the array? That would be a major problem.
Firstly, in "reset the bus": isn't the bus just an electrical wire? How
can it be "reset" and what does that do? I can understand in the case of
iSCSI the bus is maybe the TCP socket, I can somehow understand that it
can be reset, but what about physically attached disks?
I suppose "device" is the disk.. ok for that one, suppose it's doomed
I suppose "host" is the HBA card... so what does a reset of the HBA do?
Does it drop all the drives and rescan? MD wouldn't react well *at all*
to this
Thank you
J
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