[CentOS] Software RAID1 Disk I/O

Les Mikesell lesmikesell at gmail.com
Tue Jan 5 23:15:56 UTC 2010


On 1/5/2010 4:44 PM, Matt wrote:
> I just installed CentOS 5.4 64 bit release on a 1.9ghz CPU with 8gB of
> RAM.  It has 2 Western Digital 1.5TB SATA2 drives in RAID1.
>
> [root at server ~]# df -h
> Filesystem            Size  Used Avail Use% Mounted on
> /dev/md2              1.4T  1.4G  1.3T   1% /
> /dev/md0               99M   19M   76M  20% /boot
> tmpfs                 4.0G     0  4.0G   0% /dev/shm
> [root at server ~]#
>
> Its barebones right now.  Nothing really running.  I intended to move
> our current email server over to it eventually.  The thing is slow as
> mud due to disk I/O though.  I have no idea whats going on.
>
> Here is a bit of iostat -x output.
>
[...]
>
> Does anyone have an idea what I have wrong here?  This is my first
> software RAID install.  Built a number of Centos servers without RAID
> and they have all worked fine.

Did you just create the RAIDs?  It will something that size a few hours 
to complete the initial sync.  Try 'cat /proc/mdstat' to see when the 
sync completes.  Until then, expect to have head contention with 
anything else that might be trying to use the drives.

-- 
   Les Mikesell
     lesmikesell at gmail.com


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