Improve Faster IO for your filesystem by chaning the READ AHEAD Value

[root@test oracle]# df -Th /oracle
Filesystem    Type    Size  Used Avail Use% Mounted on
/dev/mapper/oracle-oracle_lv
              ext4   1008M   34M  924M   4% /oracle

[root@test oracle]# time dd if=/oracle/test of=/tmp/test count=500 bs=1M
500+0 records in
500+0 records out
524288000 bytes (524 MB) copied, 6.2385 s, 84.0 MB/s

real    0m6.249s
user    0m0.001s
sys     0m1.886s
[root@test oracle]#

[root@test oracle]# blockdev --report /dev/sdb
RO    RA   SSZ   BSZ   StartSec            Size   Device
rw   256   512  4096          0      5368709120   /dev/sdb
[root@test oracle]#


I changed the read ahead value from 256 to 1024:

[root@test ~]#  blockdev --setra 1024 /dev/sdb
[root@test ~]# blockdev --getra /dev/sdb
1024
[root@test ~]# blockdev --report /dev/sdb
RO    RA   SSZ   BSZ   StartSec            Size   Device
rw  1024   512  4096          0      5368709120   /dev/sdb
[root@test ~]#

[root@test oracle]# time dd if=/oracle/test of=/tmp/test count=500 bs=1M
500+0 records in
500+0 records out
524288000 bytes (524 MB) copied, 3.79428 s, 138 MB/s

real    0m3.819s
user    0m0.003s
sys     0m1.589s
[root@test oracle]#


The read performace has improved from 6.2 Sec to 3.8 Sec. Faster IO.