[CentOS] Adding RAM

Ross Walker rswwalker at gmail.com
Tue Dec 9 01:33:29 UTC 2008


On Dec 8, 2008, at 6:51 PM, Matt <lm7812 at gmail.com> wrote:

>>> Device:    rrqm/s wrqm/s   r/s   w/s  rsec/s  wsec/s    rkB/s     
>>> wkB/s
>>> avgrq-sz avgqu-sz   await  svctm  %util
>>> sda          0.38 176.63 70.32 78.26  813.46 2044.82   406.73   
>>> 1022.41
>>>  19.24     0.40   19.17   4.04  60.07
>>> sda1         0.00   0.00  0.00  0.00    0.00    0.00     0.00      
>>> 0.00
>>>   5.28     0.00   23.61  19.33   0.00
>>> sda2         0.38 176.63 70.32 78.26  813.45 2044.82   406.73   
>>> 1022.41
>>>  19.24     0.40   19.17   4.04  60.07
>>> dm-0         0.00   0.00 70.71 255.60  813.45 2044.82   406.73
>>> 1022.41     8.76     2.90    8.87   1.84  60.10
>>> dm-1         0.00   0.00  0.00  0.00    0.00    0.00     0.00      
>>> 0.00
>>>   8.00     0.00   64.20  11.38   0.00
>>
>> Try setting the scheduler to 'deadline' and see if the queue sizes
>> shrink.
>
> I have googled this and having a bit of trouble figuring how to change
> it under CentOS 4.
>
> http://www.wlug.org.nz/LinuxIoScheduler
>
> Does not seem to work on CentOS 4.
>
>> No raid1? Besides adding redundancy, it can help with read
>> performance. I would probably put the mail on a raid 10 though if I
>> had 4 disks to do so.
>
> I plan on moving to faster disks and RAID 1 down the road.  Just has
> not happened yet.

Setting scheduler is global in C4 it can be set as a kernel option  
with a scheduler=deadline in grub.

-Ross



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