I had a big problem Monday AM on one of my core SAP VM instances, that also happens to have a SQL DB server on it. Our VCB process finishes up on late Sunday night, if you’re not aware of how VCB works, it basically creates a snapshot of the Virtual Machine, then mounts the now readable VMDK parent to a proxy server where your backup agent resides. Once the backup is complete the snapshot is committed.  This wasn’t the case Monday AM — the VM crashed and I was paged. Snapshot didn’t commit, parent VMDK could not be found, had to manually set Parent CID in the delta VMDK file then finally when I got it back online the SQL DB was corrupt :( — luckily I had a full SQL backup from the night before.

This is where VMware KB 1007969 comes into the story…

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Posted under ESX 3.5 Tips, ESXi 3.5 Tips, Storage

Doing some speed tests of IP based storage gave me some good results. First I enabled Jumbo frames on my dedicated IP storage Ethernet card, then I set the MTU on the vSwitch and the VMKnic to 9000 (Scott Lowe has a great write-up on doing this on his website). I then mounted a NFS volume as Datastore and did a copy of a VMDK file which currently resides on a 7200rpm SATA 3 drive to the mounted NFS volume.

I copied the 8GB file in under 2 minutes and my average MbTX/s was around 525Mb (65MBps) - keep in mind, this was a copy from a local SATA disk (low IOPS) and I was able to get around 65MBps — not bad!

The biggest thing to remember, VMDK access needs low latency…not high throughput — this is why NFS has become so popular for VMDK storage.

Posted under Networking, Storage