How can we increase disk read performance in single command ?

blockdev command

This is sample output – yours may be different.

# Before test

$ blockdev –getra /dev/sdb

256

$ time dd if=/tmp/disk.iso of=/dev/null bs=256k

2549+1 records in

2549+1 records out

668360704 bytes (668 MB) copied, 6,84256 seconds, 97,7 MB/s

real 0m6.845s

user 0m0.004s

sys 0m0.865s

# After test

$ blockdev –setra 1024 /dev/sdb

$ time dd if=/tmp/disk.iso of=/dev/null bs=256k

2435+1 records in

2435+1 records out

638390272 bytes (638 MB) copied, 0,364251 seconds, 1,8 GB/s

real 0m0.370s

user 0m0.001s

sys 0m0.370sa