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

steve jenkin sjenkin at canb.auug.org.au
Wed Aug 13 22:41:01 GMT 2008

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...


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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