On Tue Oct 07, 2014 at 12:36:19PM +0200, P. Gautschi wrote:
> > What does the SMART info show for the drives - are there any reallocated
> > blocks? A large number of those scattered over the disk would certainly
> > cause seeking for both reads and writes.
>
> I will check the SMART this evening but I don't think that this is causing
> the seek. The sound is very constant and for the whole time of syncing
> the array.
> I will also run a dd on the disk to compare.
>
> > It's also worth checking whether there's anything else that would be
> > accessing the disks in the background (monitoring/indexing/etc).
>
> Unlikely because I have not yet created a filesystem after setting up
> the RAID4.
>
> > I can't think of anything else that would be causing reads to seek - SMR
> > disks or write-intent bitmaps would only affect writes.
>
> Exactly
>
> Is there any way or tool to monitor all disk read/write commands - not only
> the count or amount but every access with LBA and length?
>
You can do:
echo 1 > /proc/sys/vm/block_dump
That will write out all disk IO to the kernel log (process ID,
read/write and block offset only though). It can be very verbose,
especially if you have a lot of other things running on the system, but
you should be able to grep out the necessary lines. Echoing 0 will
switch it back off again.
Otherwise there's probably ways to get more specific results via the
kernel auditing system, but that's nothing I've played with.
Cheers,
Robin
--
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( ' } | Robin Hill <robin@xxxxxxxxxxxxxxx> |
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