Video Screencast Help

Size of Read Buffers and Number of Read Buffers

Created: 18 Sep 2012 | 4 comments
Alex Zn's picture

I try to increase read performance from storage subsystem (used for vSphere) during backup, now i use default values and perform SAN based backup.

According to technote, to improve performance i need to change parameters "Size of Read Buffers" and "Number of Read Buffers", but what should i specify ? For example maximum block size which supported on Storage Subsystem is 512K, Block size of vmfs 1M? Block of deduplication pool 64K. With default parameters i see from source storage logs block 512K and 110 IOPS.

I use Media Server 2010 R3 SP2 x64 Win2008R2.

Comments 4 CommentsJump to latest comment

ZeRoC00L's picture

Best is to try some different values, write down these values, run test-backups and see what's best for your environment.

If this response answers your concern, please mark it as a "solution"

CraigV's picture

Hi Alex,

You've posted on this before I see. Best thing to do is play around with your settings. I used to have 1MB write buffers with a block size of 128K. I wasn't bothered with read buffers.

However, the minute you go above a block size of 64K you will get a warning stating that it could corrupt data. So you need to do test restores after every change you make to ensure you can restore your data.

At some stage you will hit a plateau. What settings should be recommended in your case are very open to interpretation. My settings might not work for you, so you need to play around with the settings.


Alternative ways to access Backup Exec Technical Support:

Alex Zn's picture

So at first "Size of Read Buffers" is this option in kilobytes or what?

You say about warning, but i don`t see any, where should I see them?

I understand that I may numerate all available combinations, but I try not by myself and ask another people to test, plus, storage subsystem may show different values, cause it may be heavily loaded in some times, so i need maybe more closely understand what am i doing. I can`t find any information about what this options for, any little tehchnote, that is not enough.

CraigV's picture

OK Alex, I see where this is now. If you need to tweak these settings, just make sure you're getting backups of your registry on that server.

I've never tweaked the registry...there is only so much performance you can get out of a device and I was always prepared to do so in the Devices tab on the drive itself.

What those values are I don't know, and if you have support in place I'd recommend you open a case with Symantec for them to explain them to you.

Otherwise check and see what options you have on the device itself under Devices.


Alternative ways to access Backup Exec Technical Support: