Re: Raid5 assemble after dual sata port failure

[David Greaves <david@dgreaves.com>]

Chris Eddington wrote:
> 
> Hi,
Hi
> 
> While on vacation I had one SATA port/cable fail, and then four hours
> later a second one fail.  After fixing/moving the SATA ports, I can
> reboot and all drives seem to be OK now, but when assembled it won't
> recognize the filesystem.

That's unusual - if the array comes back then you should be OK.
In general if two devices fail then there is a real data loss risk.
However if the drives are good and there was just a cable glitch, then unless
you're unlucky it's usually fsck fixable.

I see
mdadm: /dev/md0 has been started with 3 drives (out of 4).

which means it's now up and running.

And:
sda1        Events : 0.4880374
sdb1        Events : 0.4880374
sdc1        Events : 0.4857597
sdd1        Events : 0.4880374

so sdc1 is way out of date... we'll add/resync that when everything else is working.

but:
>  After futzing around with assemble options
> like --force and disk order I couldn't get it to work.

Let me check... what commands did you use? Just 'assemble' - which doesn't care
about disk order - or did you try to re-'create' the array - which does care
about disk order and leads us down a different path...
err, scratch that:
>  Creation Time : Sun Nov  5 14:25:01 2006
OK, it was created a year ago... so you did use assemble.


It is slightly odd to see that the drive order is:
/dev/mapper/sda1
/dev/mapper/sdb1
/dev/mapper/sdd1
/dev/mapper/sdc1
Usually people just create them in order.


Have you done any fsck's that involve a write?

What filesystem are you running? What does your 'fsck -n' (readonly) report?

Also, please report the results of:
 cat /proc/mdadm
 mdadm -D /dev/md0
 cat /etc/mdadm.conf


David