UNIX for Dummies Questions & Answers

hi guys

right now I have 6 Virtual Machines (VMs) running on Vmware ESXi 5.1 and attached to Storage SAN.
All these run Suse Linux 11 SP1 x64.

All of a sudden 1 of these VMs is running very slow making high CPU usage and I see al wait % kinda high 40-50%. Apparently since I don't own this virtual server the server was running fine and last change made was increasing memory

so I found out that test hard disk performance must be the issue
VM having issues. It so slow that I cancel the command but it's running at 2.7 MB

Code:

dd if=/dev/zero of=test bs=1048576 count=2048
781+0 records out
818937856 bytes (819 MB) copied, 298.699 s, 2.7 MB/s

running dd command on any of the other VMs linux server is about 280MB - 310 MB/s

Code:

dd if=/dev/zero of=test3 bs=1048576 count=2048
2048+0 records in
2048+0 records out
2147483648 bytes (2.1 GB) copied, 7.64361 s, 281 MB/s

any idea what could be causing this issue or how to fix it?

thanks a lot

It's hard to tell without access to server.

You might want to check the iostat output on the machine.
If the values are high, check the machine for processes doing intensive disk operations.

Also, you might want to check on your storage if the actual spindles (physical disks) are being shared to some other hosts doing intensive I/O.

Check the FC switch port for possible errors.

Regards
Peasant.

I already moved the VM to another storage another SAN zone so taking storage out of question, well I have really really fast storage working on this

It seems this can happen after a move of the VM.
Work-around: switch auto-move off for SuSE VMs. Manually move them, and reboot them if performance becomes bad and/or system load becomes high.

do you mean storage vmotion? or anotehr setting?

thanks a lot

Maybe even short stops can cause this. In this case - yes.