On 10/31/2016 3:29 PM, Wols Lists wrote:
On 30/10/16 18:56, TomK wrote:
We did not do a thorough R/W test to see how the error and bad disk
affected the data stored on the array but did notice pauses and
slowdowns on the CIFS share presented from it with pauses and generally
difficulty in reading data, however no data errors that we could see.
Since then we replaced the 2TB Seagate with a new 2TB WD and everything
is fine even if the array is degraded. But as soon as we put in this
bad disk, it degraded to it's previous behaviour. Yet the array didn't
catch it as a failed disk until the disk was nearly completely
inaccessible.
What is this 2TB Seagate? A Barracuda? There's your problem, quite
possibly. Sounds like you've got your timeouts correctly matched, so
this drive is responding, but taking ages to do so. And that's why it
doesn't get kicked, but it knackers system response times - the kernel
is correctly configured to wait for the geriatric to respond.
Cheers,
Wol
Hey Wols,
It's about a 2-3 year old Seagate but not a Barracuda. They did not
come with high ratings back then. I also do adjust other recommended
settings like write caches etc.
With the previous answer provided by Andreas, I got a very good picture
what scope of issues RAID should cover and what is not.
So rightly so there is a gap where RAID will not cover all disk failures
while the disk may impact the applications sitting on top of the array.
Where I was going with this as well is to help me identify what other
tools I may need in solutions that use RAID. In this case the answer
Andreas provided tells me I have to have specific software for disk
monitoring to the array that would tell me potential issues ahead of
time alongside the RAID.
On a side note, I like to see the RAID mailing lists so busy. If I were
to read the various blog posts, I would believe RAID died 5 years ago. :)
--
Cheers,
Tom K.
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