[OpenIndiana-discuss] ZFS read speed(iSCSI)

[Christopher Chan]

On Thursday, June 06, 2013 06:52 AM, 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
>
> The Hyper-v systems has 2 interfaces in LACP and all show as active and
> windows indicate 2Gbps, never go over 54% util.
>
> When I copy to an iSCSI disk from a local disk, it copies at around 200MB/s
> and thats fine. When I copy from the iSCSI disk to the local disk I get no
> more that 80-90MB/s and that is after messing around with the TCP/IP
> setting on Windows. Before the changes it was 47MB/s max. (copy from the
> local disk to the local disk I get 107MB/s so that is not the issue)
> VMware 5.0 will not get more than that either.

I may be wrong but I don't think a single connection will be split over 
two interfaces in LACP to achieve higher throughput. If you have 
concurrent connections then perhaps you may see more throughput.

>
> Even when I do a zfs send/recv is seems that reads are slower. I assume
> this is the expected behavior.

zfs has to seek all over the place to find the snapshots which slows 
things down.