EVA 8400 I/O Size

 
mattwaddy
Occasional Advisor

EVA 8400 I/O Size

Now I have read from numerous sources that it is best practice to set the I/O Size to 128K when using windows 2008 and / or VMWare. We see a large amount of processor utilisation during busy periods such as backups these are done using classic HP Dataprotecor backups backing up as you would a phyiscal machine so not ideal. However we also found we had a large amount of mirror port activity for proxy reads which is now sorted, however I'm wondering how much difference the I/O change has made for people?

 

Last time we tried to make the change was at the same time we did a firmware upgrade and a couple of other changes to backups etc at which point we had to roll back due to not knowing what caused the actual issue. I'm now struggling to get buy in for changing this setting on VMWare hosts and windows due to those issues last time, which I feel were unrelated.

 

If anyone can advise on improvements seen, particullary if it effects processor utilisation that would be appreciated.

3 REPLIES 3
giladzzz
Honored Contributor

Re: EVA 8400 I/O Size

hi

you must set the IO size to 128K because of how the EVA works because if not the controlers we be loaded with high delays

Use of VMware ESX 4, which allows the maximum IO-size as issued by VMware to be restricted to 128Kbytes.

The default is 3Mbytes and changing this value requires a reboot of the ESX server.

Using Vcenter client, From ESX Server Configuration tab, on the left sidebar,

under Software, select Advanced Settings, select Disk and scroll down to find [Disk.DiskMaxIOSize] option and change the value in the [Disk.DiskMaxIOSize] field to 128.

Click OK and reboot the ESX server.

 

 

For Microsoft windows 2008 Emulex and QLogic Driver use CUSTOMER ADVISORY

http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?lang=en&cc=us&objectID=c02518189&jumpid=reg_R1002_USEN

 

Regrards

press the kudos star if you liked

 

mattwaddy
Occasional Advisor

Re: EVA 8400 I/O Size

Would that be seen on the processors utilisation as an increase also? As in the controllers need to split the large io chunks into smaller native 128KB chunks?

 

Have you experienced a before and after graph that shows what the changes would look like?

giladzzz
Honored Contributor

Re: EVA 8400 I/O Size

Hi

I don't have a before and after but I know that because before the controllers have to split data into smaller chunks on loaded systems there a great impact on performance this can cause timeout when accessing the EVA

Regards