On 10 October 2013 15:07, steve-ALUG@hst.me.uk wrote:
New microserver? New as in brand new?
Yes, brand new. 250GB HDD as supplied with the microserver has Ubuntu 12.04 (server, amd64) on it, then 4x2TB drives installed to be used as RAID5 array for storing backups.
So it works then it stops working. Could it be a timeout issue? I.e. it writes to the disk, then spends a while writing to the other one, in the mean time, the first one has powered down and won't spin back up again?
Possibly. I don't know what would cause mdadm to "give up", but it might not expect the drives to power down after 8s of inactivity. (Aside: anyone with WD "green" disks would be advised to check whether they are running up large Load_Cycle_Count counts; anecdotal evidence (ie I read it in a forum somewhere) suggests other manufacturers have this "feature" too. Any figure over 1000 (except for an old disk) should be considered high, I believe.
Try disabling power saving, disks spinning down etc.
From my efforts with Google these drives don't like having the power
saving turned off but setting to 300s should suffice, which is what I have done.
Grasping at straws, is the power supply at your location reliable? Could it be brown-outs messing things up.
Anything is possible but if so it's only this set of disks that's showing it. I have other mdadm-based RAID arrays in other boxes in the same building (not sure off the top of my head whether any are RAID5, most will be RAID1).
Are you using the latest O/S, with all the patches installed?
If latest LTS counts as "latest" then yes (including up to date on patches).
5hrs remaining until the RAID build is due to complete so I guess I'll know in the morning...
Thanks everyone for the suggestions and advice.
Mark