[clug] Dual-ported disks - or accessing disks from 2 systems

steve jenkin sjenkin at canb.auug.org.au
Wed Aug 13 23:15:48 GMT 2008

steve jenkin wrote on 14/8/08 8:41 AM:

Ummmm. Don't want to seem ignorant or lazy by answering my own question.
[I'm still v. interested in iSCSI & eSATA, please don't let up on those]

But one answer is Firewire - it supports multiple hosts on the same bus
- is why it can be used for IP (as well as things like fibrechannel &
infiniband - which are switchable, but out of $$ reach).

This isn't exactly what I had in mind, but points there.

The hint was in wikipedia - 1394a supports multiple hosts.

> I'd like to be able to access a disk from two different systems,
> /cheaply/.  Anyone done this or seen it done?
> *Not* simultaneously update the same filesystem, but just to fail-over.
> Last time I did this was SUN + fibrechannel + disk array + Veritas.
> Out of the ballpark for this application :-)
> I have a hack that should work, though the manufacturer doesn't
> guarantee it. I've a Lantech Nexstar-3 with multiple-ports (USB,
> firewire, ...) *all* are active at once. I've confirmed connecting
> simultaneously won't damage the electronics. But the semantics of which
> interface gets priority is unclear & this mode not officially supported.
> What I'd *really* like is something based around SATA/e-SATA - do SATA
> switches exist? Ie. connect two HBA's to one device.
> Or if anyone can recommend a good/cheap iSCSI setup, that'd be interesting.
> Can anyone tell me how much CPU overhead & network bandwidth iSCSI burns?
> A good fallback position for me is a NSLU with USB attached disk.
> But that introduces yet another point of failure...
> cheers
> steve

Steve Jenkin, Info Tech, Systems and Design Specialist.
0412 786 915 (+61 412 786 915)
PO Box 48, Kippax ACT 2615, AUSTRALIA

sjenkin at canb.auug.org.au http://members.tip.net.au/~sjenkin

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