Linux DD read Write disk speed

Time has a timing function, DD is used for copying, read from If, write to of. If=/dev/zero does not produce IO, so it can be used to test write speed. Similarly of=/dev/null does not produce IO and can be used to test the read speed. BS is every time you read or write

Size, which is the size of a block, count is the number of read-write blocks.

Specifies the speed at which read, write files to the hard disk

1. Write speed of the disk where the test/directory resides:

[[Email protected]/]# time DD If=/dev/zero bs=1024 count=1000000 of=/1gb.file

1000000+0 Records in

1000000+0 Records out

1024000000 bytes (1.0 GB) copied, 2.57314 seconds, 398 MB/s

Real 0m2.787s

User 0m0.920s

SYS 0m1.867s

This is because the time is used to display, linux5 do not need to use, in the linux4 is not (1024000000 bytes (1.0 GB) copied, 2.57314 seconds, 398 MB/s) part, so the time command to count

The time to calculate the replication.

2. Read-only speed of the disk where the test/directory resides:

DD If=/kvm/ftp/other/1gb.file bs=64k |DD of=/dev/null

382860+0 Records in

382860+0 Records out

3136389120 bytes (3.1 GB) copied, 68.38 seconds, 45.9 MB/s

Real 1m8.406s

User 0m0.039s

SYS 0m4.573s

3. Test read and write speed (what this is):

DD If=/vat/test Of=/oradata/test1 bs=64k

Dd:writing '/oradata/test1 ': No space left on device

5025+0 Records in

5024+0 Records out

329261056 bytes (329 MB) copied, 23.8813 seconds, 13.8 mb/s

Note: The larger the amount of replication is theoretically the more accurate the test.

2010-07-05

This article is from the "Five Corners" blog, please be sure to keep this source http://hi289.blog.51cto.com/4513812/1791945

Linux DD read Write disk speed