Really high disk i/o !!

[shahzaib shahzaib]

Our server HDD i/o is constant on 8MB/s and i/o utilization + await is very
high due to which nginx video streaming is really slow and we're receiving
complains from our users regarding slow streaming of the videos.

We're using 12X3TB SATA HDD Hardware-Raid10 with 16G RAM
OS Centos 6.4

 8MB/s w/r should not be issue for 12X3TB SATA HDD. Maybe i need to tweak
some nginx buffers or kernels in order to reduce the high io wait ?

Could someone point me to the right direction ? We can't afford SAS Drives
right now and have to go with the SATA.

Linux 2.6.32-431.17.1.el6.x86_64 (storage17)    06/16/2014
_x86_64_        (8 CPU)

Device:         rrqm/s   wrqm/s     r/s     w/s   rsec/s   wsec/s avgrq-sz
avgqu-sz   await  svctm  %util
sda             123.66   336.85  118.87    7.67 19496.19  2759.42
175.88     2.40   18.93   6.27  79.35

Device:         rrqm/s   wrqm/s     r/s     w/s   rsec/s   wsec/s avgrq-sz
avgqu-sz   await  svctm  %util
sda              75.00     8.67  108.00    2.00 18117.33    85.33
165.48     1.88   17.05   6.86  75.47

Device:         rrqm/s   wrqm/s     r/s     w/s   rsec/s   wsec/s avgrq-sz
avgqu-sz   await  svctm  %util
sda              76.00     0.00   94.00    0.33 17192.00     2.67
182.28     1.50   16.04   7.47  70.47

Any help would be highly appreciated.

Regards.
Shahzaib
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