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May 15, 2011


Erik Zandboer

I was looking through the report, and it seems that the maximum bandwidth usage was set at 128 VMs having 256 total outstanding I/O's of 4KB each, delivering a total bandwidth usage of 1MB/s through the protocol under test. Is this correct?

Michael Ryom

Theres some talk over at http://www.yellow-bricks.com/2011/05/16/surprising-results-fcnfsiscsifcoe/

Would be cool if you would comment on that ?

Vaughn Stewart

@Erik - There are two models which one deploys storage with vSphere, which I will refer to as shared & isolated datastores. In this TR we review both. Shared in sections 3 & 4, and Isolated in section 5.

Shared datastores are large pools typically comprised of multiple VMs, where each VM commonly has low to moderate I/O requests. Shared datastores commonly contain 5-15 VMs with SAN protocols (FC, FCoE, iSCSI) and 60-200 VMs with NAS (NFS). While each VMs I/O load is not large, the aggregated I/O load is rather large.

Isolated data stores are smaller pools comprised of a single VM that has high I/O requirements, such as an OLTP database.

From the details of your question, IOMeter settings including outstanding I/O and block size, applies to the shared datastore tests of section 3.

IOMeter sends I/O requests asynchronously, resulting in an aggregate I/O load on the data store that can be measured in the hundreds of MB/s and tens of thousands of IOPs. I wish I could share with you the actual results, but VMware engineering specifically requests that we only publish relative numbers.

Trust me here; the workload on the shared datastore is massive.


BTW - There’s additional conversation on this topic here: http://nt-ap.com/jzOO9G


Hi Vaughn. Would that be feasible the performance engineers post the IOmeter Configuration Files (.ICF) they used to benchmark this environment?

They can be recreated from the report though, but that would be great if that is available online...


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