On 1/28/2015 11:07 PM, John R Pierce wrote:
On 1/28/2015 4:32 AM, Jatin Davey wrote:
I am using RHEL 6.5 on my server.
From top command i can see that the processors in my server are
spending a lot of time on wait for I/O.
I can see high percentage in terms of 30-50% on "wa" time.
Here is the df output about the disk space in my system:
**********
[root@localhost images]# df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sda1 1915071844 103227908 1714563936 6% /
tmpfs 32931472 0 32931472 0% /dev/shm
**********
Could someone point me on how to improve the disk I/O on my server
and reduce the wait time on I/O.
it appears you have everything on a single file system on a single 2TB
drive?
[Jatin]
Yes , entire disk is mounted on a single file system. Will this cause
high wait time for I/O operations ? Do you think splitting it into
multiple partitions would help ? Appreciate if you can enlighten me in
this regard or provide pointers to it.
I'm going to guess thats a desktop grade SATA disk spinning at most at
7200rpm (many are slower, 'green' disks are often 5400rpm).
[Jatin]
Yes , it is a SATA disk. I am not sure of the speed. Can you tell me
how to find out this information ? Additionally we are using RAID 10
configuration with 4 disks.
what sort of workload are you running?
[Jatin]
Our workload is a bit high on disk reads / writes and hence i am seeing
slowness in it when using the top command. We basically run VMs on the
RHEL 6.5 host. Our target is to house 5-6 application VMs on this host
and ship this as a product on a rack server.
our high disk IO servers, doing things like transactional databases,
have many 10000rpm or 15000 rpm drives on a SAS2 raid card with 1GB or
2GB of write-back-cache (battery or flash backed).
Hi John
Please see my responses inline. Appreciate your inputs in this regard.
Thanks
Jatin
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