Slow performance for Ralus backups may be related to direct memory access for the mounted volumes on the server.

Article:TECH87600  |  Created: 2009-01-15  |  Updated: 2012-10-04  |  Article URL http://www.symantec.com/docs/TECH87600
Article Type
Technical Solution

Product(s)

Environment

Issue



Slow performance for Ralus backups may be related to direct memory access for the mounted volumes on the server.


Solution



Hdparm application provides important information on direct memory access for volumes mounted on Linux servers.

hdparm [Option ] [device] ..

This tool is based on install of the distribution and my not be installed.

Description:

hdparm provides a command line interface to various hard disk supported by the stock Linux ATA/IDE/SATA device driver subsystem. Some options may work correctly only with the latest kernels. For best results, compile hdparm with the include files from the latest kernel source code.

hdparm ?c1d1X66 /dev/hda

-c1 enables 32-bit I/O
-d1 enables DMA
-X66 enables ATA/33


To enable DMA on a device type the following:

hdparm -d1 /dev/hda


Speed Test Example:
hdparm -Tt /dev/sda1
Timing cached reads: 3120 MB in 2.00 seconds = 1560.00 MB/sec
Timing buffered disk reads: 38 MB in 0.73 seconds = 52.05 MB/sec



Legacy ID



325202


Article URL http://www.symantec.com/docs/TECH87600


Terms of use for this information are found in Legal Notices