On 1/17/15 21:47 , Greg Zartman via smartos-discuss wrote:
> I'm curious if anyone has some general read/write speeds for a Centos VM
> running on smartOS.  I know there are alot of variables to this question,
> but I'm just looking for general numbers.  I've created a Centos VM and
> then mounted zfs a couple zfs volumes using nfs thinking I may get better
> disk speed than putting this data on the centos filesystems on top of zfs.
> However, I'm just seeing around 60MB/s in the VM, but north of 300MB/s in
> the headzone to this zfs volume.

In this case, you need to make sure you're doing an apples to oranges
comparison. By default all disk I/O that a KVM instance does is
synchronous I/O. If your test in the global zone isn't doing synchronous
I/O, then it's not going to be a like for like comparison. How are you
performing your comparisons?

If you don't have a slog in your machine, and you care about guest I/O
performance, then I'd look at that.

> I'm wondering if this is the virto driver or if I'm really losing this much
> to nfs.  I thought that using nfs would bypass the virto drive, but maybe
> it doesnt??

It bypasses the virto disk driver; however, it instead uses the virtio
networking driver to transmit the RPC requests.

Robert


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