rooling replication and many pop3d

[Andy Bennett]

Hi,

>> What IO subsystem do you have on this machine? What filesystem are you
>> using?
> 
> I have  4 HDD 500GB S SATA II
> with LSI 8704 ELP SAS
> RAID 6
> filesystem ext3 mounted with noatime, nodiratime


> this my vmstat after I run the command   find -type f | xargs cat > 
> /dev/null  :
> 
> http://www.digicolor.net/cyrus/img7.jpg

This is a very sad set of numbers. :-( It's still really, really choppy
and the dead spots don't seem to correlate particularly well with bo
activity.

Have you got someone who can help you debug your storage array and
ensure that it's not degraded in some way? Is the battery empty? Are
there any disks which are failing? Do all the disks have their write
caches and retry handling set up correctly?

How old is your file system? Have you been running it near capacity
(>70% full) for long periods of time?

You might be able to tell whether you have a file system problem or an
array problem by comparing your previous vmstat with the results
obtained from 'sudo /sbin/haparm -tT /dev/<spool dev>'. For reference,
on my disk I get:

-----
$ sudo /sbin/hdparm -tT /dev/sda

/dev/sda:
 Timing cached reads:   3272 MB in  2.00 seconds = 1637.05 MB/sec
 Timing buffered disk reads:  194 MB in  3.02 seconds =  64.18 MB/sec
-----

I'd certainly not expect anything less from your array. I'd hope for at
least 100MB/sec if not a lot more.






Regards,
@ndy

-- 
andyjpb at ashurst.eu.org
http://www.ashurst.eu.org/
0x7EBA75FF