Disk related operations slow on VM

[Olga_1]

Hello,

We have VM host (HP-UX i64 11.23) with 3 VM guests (HP-UX i64 11.23).

Problem: Disk related operations (copy, uncompress files, etc.) on VM guest are 3 times slower then on the host.

Is it normal? Or we have a set up issue?

Thank you for any information.

[Torsten.]

What is your backing store setup (LVOL/file/raw disk)?

What version of HPVM do you run?

[Olga_1]

version A.03.00 Integrity VM .

set up:

VM host has two vg.

On vg01 we have three file systems, each of the FS has two files Disk1 and Disk2

[Michael Steele_2]

Hi Olga:

Let's try to isolate the problem file system with sar. Do you keep 24 hour sar data in /var/adm/sadm? If not, then you'll have to set up a 15 minute cron script to sample performance data in real time for a 24 hour period and pipe the data into a save file. Here's what I need:

sar -v 5 5
sar -d 5 5
sar -uM 5 5
UNIX95=1 ps -e -o vsz,rss,pid,ppid,comm | sort -rn | head
UNIX95=1 ps -e -o pcpu,vsz,rss,pid,ppid,comm | sort -rn | head
UNIX95=1 ps -e -o time,pcpu,vsz,rss,pid,ppid,comm | sort -rn | head
UNIX95=1 ps -e -o etime,time,pcpu,vsz,rss,pid,ppid,comm | sort -rn | head

Additionally, your server archicture and disk array setups. In particular, how many HBA's, raid levels, disk groups etc.

[Eric SAUBIGNAC · Accepted solution]

Bonjour Olga,

2 things :

- There is a new version of HPVM. Here is an extract of what you can read in HP's documentation :

"The HP Integrity Virtual Machines A.03.50 release introduces accelerated storage and networking I/O products (AVIO) to improve the overall I/O performance. The Accelerated Virtual I/O (AVIO) products provide up to 60% reduction in service demand and as much as twice the throughput over the existing virtualized storage and networking Integrity VM solutions."

I have not yet tested this version, but I guess you should ...

- You said "VM host has two vg. On vg01 we have three file systems, each of the FS has two files Disk1 and Disk2".

Should I understand that your backing store is a file ? If yes, I guess you have done the worst choice in term of performance, sorry ;-)

You can have a virtual disk in your VM in three ways : a physical disk presented as a raw device, a logical volume or a file. The most performant is supposed to be raw device, then lvol and finally file.

My choice is to work with raw devices when it is possible and logical volume if not, for example if I need to achieve high availability through LVM Mirror.

I think that in the future I will work only with LVM as backing store : from HP's support it seems that performance with LVM is at the same level than with raw devices.

Hope this will help

Regards

Eric