Hello,
I'm trying to track down performance issues in our esx(i) 3.5 servers. I've been reading all the vmware docs, mostly working with esxtop.
My understanding is that cmd/s in resxtop are the same as iops.
On one new server, a sunfire x4150, with 8 SAS 10k 137GB disks in raid 10. This should provide a theoretical IOps (if one disk is 125) of 500. If I run IOmeter in a windows 2003 VM, I can easily push 1000+ IOps, as reported by IOmeter and resxtop. I've given IOmeter an 8GB file (VM has 4GB of RAM), so there shouldn't be a cache in the way.
Using the same methodology on my HP DL385s and the reports IOps seems to be inline with the theoretical.
I've tried other tools (in a linux guest, iozone and bonnie+) and resxtop reports very large cmd/s. With the right workload I can reach 3500.
I must be missing something. Any suggestions as to what I might be over looking?
Thank you.
My understanding is that cmd/s in resxtop are the same as iops.
I don't think so, IOPS is the DISK performance, cmd/s is the number of COMMANDS sent to the disk. Not the same thing. A high amount of commands just means there is a lot of chattering to the DISK, doesn't mean those commands are doing anything useful.
Add the reads/s and writes/s to get your IOPS.
http://communities.vmware.com/docs/DOC-5240
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You can also get the IO information easily from the VI client under the performance tab. Sometimes it's easier to find and read what your looking for there.
David Strebel
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>> My understanding is that cmd/s in resxtop are the same as iops.
Yes, it is. cmds/s ==> I/O commands issued per second.
>> On one new server, a sunfire x4150, with 8 SAS 10k 137GB disks in raid 10. This should provide a theoretical IOps (if one disk is 125) of 500.
Depends. If you are talking about 8K 100% random 100%writes, then Yes. For 8K 100% random 100%reads, you can expect 1000 IOps.
>> I've tried other tools (in a linux guest, iozone and bonnie+) and resxtop reports very large cmd/s. With the right workload I can reach 3500.
What is the I/O profile you used to push 3500+ IOps?
Chethan