[OpenIndiana-discuss] ZFS read speed(iSCSI)

[Saso Kiselkov]

On 05/06/2013 23:52, Heinrich van Riel wrote:
> Any pointers around iSCSI performance focused on read speed? Did not find
> much.
> 
> I have 2 x rz2 of 10x 3TB NL-SAS each in the pool. The OI server has 4
> interfaces configured to the switch in LACP, mtu=9000. The switch (jumbo
> enabled) shows all interfaces are active in the port channel. How can I can
> verify it on the OI side? dladm shows that it is active mode
> 
> [..snip..]

Hi Heinrich,

Your limitation is LACP. Even in a link bundle, no single connection can
exceed the speed of a single physical link - this is necessary to
maintain correct packet ordering and queuing. There's no way around this
other than to put fatter pipes in or not use LACP at all.

You should definitely have a look at iSCSI multipath. It's supported by
VMware, COMSTAR and a host of other products. All you need to do is
configure multiple separate subnets, put them on separate VLANs and tell
VMware to create multiple vmkernel interfaces in separate vSwitches.
Then you can scan your iSCSI targets over one interface, VMware will
auto-discover all paths to it and initiate multiple connections with
load-balancing across all available paths (with fail-over in case a path
dies). This approach also enables you to divide your storage
infrastructure into two fully independent SANs, so that even if one side
of the network experiences some horrible mess (looped cables, crappy
switch firmware, etc.), the other side will continue to function without
a hitch.

Cheers,
-- 
Saso