Bit of a weird one this. I want to take two hard discs and join them together under Linux. No, I don't want a RAID set - these discs are part of a RAID set in an external enclosure, so the redundancy is already there. I just want to stitch them together to make one big drive.

My problem is, my SCSI HBA seems to get grumpy with LUNs of more than 2TB, and won't let me see them. I want to make a ~3TB drive for backups, so I'd like to join 2 LUNs together.

It doesn't need to boot off it or anything. Any ideas?

You've got a good one there :-) I thought you could get away with creating some kind of logical partition that spans both disks, but after having a little search round t'interweb I can't seem to find anything about it... I found one reference to a guy having succeeded, and that he would test it and report back, but he never did...

I'll have an ask of some of my really geeky linux mates (geekier than me)

Jon.

I remember doing it before in NetWare (3 - that's a while back). It may be that I just need to figure out why the hell my Adaptec card in this server won't see >2TB LUNs...

I could RAID0/1 it with md, but I don't want to because there'll be a *much* bigger CPU overhead involved there.

Haven't touched Linux for years but a quick google came up with this - hope its what you're after.

That would work perfectly. I'm starting to have different ideas though - I can add several 2TB LUNs and just backup different hosts to different LUNS on different schedules. It's a bit more wasteful than linking the drives together, but less likely to have any problems. I mean, if a Logical Volume has trouble I lose the lot...

The other option, which I'll look at next time I'm doing upgrades, is to swap out the stupid Adaptec HBA for one that will actually handle more than 2TB in a single drive (which, let's be honest, isn't *that* much these days...)

Anyway, thanks for that, but I'm going to go another direction

Quick update. Put in a dual-channel LSI SCSI HBA (21320), and it seems to just work. Like it should.

A few days later, and I've got a 4700GB drive formatted and working. Yay!