On Sun, Jun 2, 2013 at 6:53 AM, Phil Turmel [off-list ref] wrote:
[trim /]

There are numerous discussions in the archives...  search them for
combinations of "scterc", "tler", and "ure".

It appears this has been a frequent issue over the last year. Thank
you for the background information, I understand what I was reading.

So your device role order is /dev/sd{c,b,d,e}1.

[trim /]

Anyways, the quickest way for you to have a running array is to use
"mdadm --assemble --force /dev/md0 /dev/sd{c,b,e}1".  This leaves out
the first dropped disk.  Any remaining UREs cannot be corrected while
degraded, but the data on the first dropped disk is suspect.

Feel free to use an overlay on /dev/md0 itself while making your first
attempt to mount and access the data.  If you cannot get critical data,
stop and re-assemble with all four devices.

Phil

Thanks, I will do that.

I am correct in thinking that I should not set scterc to 7 seconds
initially, since there will not be any parity to correct the read
errors? Best would be to set the driver time-out to 180 seconds until
after the array is rebuilt?

I am concerned about read errors during the rebuild. With a failed and
rebuilding array, will the get drive kicked on an URE? Is it better to
use something like badblocks or dd_rescue to correct/mark the sectors
first and then rebuild? Either way, I'm going to lose that data, but
maybe there are some better tools for extracting data from a bad
sector?

After the rebuild is complete, I should set the scterc to 7 seconds
and add a bitmap based write-intent log?

Does anyone learn these things the easy way :)

Much appreciated, Chris