[OpenIndiana-discuss] Linux software-raid with two Comstar iSCSI volumes

[Timothy Coalson]

On Thu, Nov 15, 2012 at 5:38 AM, Florian <florian at acw.at> wrote:

> Hello,
>
> has someone experience with Linux software-raid with two Comstar iSCSI
> volumes from two OI servers?
>
> I tested this on a virtual machine, but it would be great, if I can get
> some  experience with such a combination!
>
> Will this work without problems? The Linux Server is connected through one
> Gbit Interface to a switch and this switch is connected to the two OI
> servers. Will there be a bottleneck? Can I get full Gbit speed or is this
> speed divided due to the mirroring of the iSCSI volumes?
>

Just from how linux software raid1 works, I would expect your maximum write
throughput to the md device to be half the network throughput, since it has
to write every block to both servers through one link.  Reading is likely
to only read any given block from one device, so full network throughput is
likely there (assuming no congestion, etc).

Gigabit network with theoretical peak at 125MB/s will probably be your
bottleneck unless the pools containing the zvols have rather poor
performance.

Tim