Re: [Xen-users] Network based storage - NBD/AoE/iSCSI other?

[Pasi Kärkkäinen <pasik@xxxxxx>]

On Sat, Sep 30, 2006 at 07:38:41PM +0100, Ian P. Christian wrote:
> I'm currently investigating setting up few Xen servers.  I've noticed
> that currently live migration of Xen's require you to use a network
> based storage system.
> 
> So, I've looked at a few of the options, and they all strike me as
> reasonably 'new' to linux, so I'm not sure how stable these options are.
> 
> iSCSI looked like a good bet, but the fact it's using TCP/IP seems like
> a crazy overhead to use when I'm most likely going to be hosting the
> storage on the same layer 2 network as the servers.
>

iSCSI is nice, you can play and test with your own custom iSCSI server
(=target), maybe done with Linux iSCSI Enterprise Target software and
software raid + lvm.

If you need more speed, reliability and manageability, you can buy some of
the "hardware" targets.. for example Equallogic PS-series:

with 750G 7.2K SATA2-drives:
http://www.equallogic.com/products/view.aspx?id=1791

with 146G 15K SAS-drives:
http://www.equallogic.com/products/view.aspx?id=1989

Those will give you 60 000 IOPS per box.. and 300 MB/sec (3xGE per box).

They also contain "group management", so if you have 1 or 20 boxes, you
still manage (and use) them like 1 box. Automatic load-balancing between
boxes and ports. 

- Pasi
 
> AoE solves that above concern but I'm confused as to what would happen
> should I need to move from SATA storage drives to SCSI for performance
> reasons.
> 
> Someone also advised my against NBD saying that his notes suggest that
> it will not start servicing a second write untill the first has completed.
> 
> Having googled I've not found a huge amount of documentation on any of
> these options, and I'm unsure as to what option to do with.  I was
> hoping people might take some time to write to the list with their
> experiences with these technologies.
> 
> Many thanks,
> 
> -- 
> Ian P. Christian ~ http://pookey.co.uk
> 

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