OK real quick short post here. I figured I’d take a snapshot of my vCenter server (reason will be next blog post). In this case I decided to snapshot the VM with memory saving, I figured it would be faster than bringing the VM back up from a shutdown state as that’s what a normal snapshot would do.
In most cases that would probably be a fair assumption, but boy was I wrong.
It Took a short time save the snapshot but almost 15 min or more to bring the VM back to full operational status with all memory back in tact… just check out these charts:
Here you can see it took maybe 5 min to save the memory state to disk, this would have been a time of 0 minutes since a normal snapshot doesn’t save memory to disk. Then you can see the slower longer recovery time it took to get the same memory from disk and put it back into memory.
Of course taking a solid guess that disk I/O is much slower than Memory I/O the bottle would have to be non other than the actual disk….
Yup there’s the same matching results of fast disk writes, and slow disk reads…
and there’s the disk being 100% bust on the read requests. I’m not sure why the read performance on this drive was as bad as it was, but I have a feeling a regular boot would have been faster… I’ll update this post if I do an actual test.
Meh, pretty much same amount of time… I think I need some super fast local storage… yet I’m so cheap I never do…. cheap bastard…