LTO-4 recommendations for PPC G5?

[theboyk]

Hello.

 

I'm currently running Retrospect 6.1 Server on a dedicated Macintosh G5 (Dual 1.8Ghz, max RAM). It's used to back up about 25 machines, all Mac (note: not backing up the entire machine, just a specific "Work in Progress" folder on each machine). Backups are to a Sony AIT-2 Turbo drive via FireWire.

 

I need to upgrade the tape system to something a little more modern. I've been looking at the AIT-5 drives, but I'm leaning towards an LTO-4 solution. So, I'm wondering if anyone has any recommendations on an LTO-4 setup that would work with the G5? It has to be an external LTO-4 drive since I don't think there's any way of getting one into the G5 itself. So, along with the LTO-4 recommendation, I'd also be looking for a solution for hooking up said drive to the G5 (the G5 has three open, full-length 33MHz, 64-bit PCI slots).

 

Any advice?

 

Thanks,

Kristin.

 

[rhwalker]

Two comments.

 

(1) if you go SCSI, the only choice is the ATTO UL4D for the HBA.

 

(2) get an autoloader, it's the only way to do tape. It will change your life. Really.

 

Exabyte (now Tandberg) has several.

 

russ

[theboyk]

Thanks Russ!

I think the ATTO UL4D is PCI-X — my G5 is only PCI — any PCI solutions? I have the option to take over another G5 that's got PCI-X, but it'd take some work...

Thanks again!

k.

 

[rhwalker]

Ok. I now see from the specs that some of the Dual 1.8 PPC G5 machines were PCI; you didn't initially say which you have.

 

According to the specs, the UL4D also works in standard PCI. I've only tried ours on PCI-X in our G5 xServe.

 

While the UL3D (now discontinued) is PCI only, I don't think that there are modern OS X drivers for it, which is why I would suggest the UL4D.

 

Russ

[theboyk]

Sorry, thought I mentioned I only had PCI available in the G5 — and yea, I checked the data sheet and it is backwards compatible with PCI, though, I think I'd gain some performance with PCI-X (agree?). Do you think PCI would give me a performance hit? Like I said, I can get access to a G5 tower with PCI-X, it'd just take some shuffling around, so if it'd make a big difference, it'd be worth the effort. Still on this topic, is SCSI the way to go, or is SAS an option worth looking at?

 

So, I've been looking at the Tandberg LTO-4 drives. What are you opinions on full-height versus half-height? I mean, do you think it'd be the drive, even at half-height speeds, that would ever been the bottleneck? Personally, I'd think if anything it'd be HD speeds from where the source data would be (ie. old G5s)? Or maybe the PCI on the G5 (to which the LTO-4 drive would be attached)? I'm not too concerned over network speeds as I've recently rebuilt our network (before moving into a new space) installing 120+ individual dedicated gigabit lines to a stack of gigabit switches, thus allowing every machine it's own dedicated gigabit line (getting max speeds).

 

Finally, I've been looking into the idea of the autoloader, but not sure if I'd get the benefits given the backup policy I have to work with?

 

The backup policy works on an alternating set/cycle. Set 1 runs nightly on Monday/Wednesday/Friday/Saturday/Sunday and the other set runs nightly on Tuesday/Thursday. This allows me to take the previous days tape off site each night. We require off-site storage for all backups (even though a day behind, current work as backups take place post-workday when everyone has gone home/computer are no longer in-use). Each client machine has a "work in progress" folder and this is the folder that gets backed up each night. Once a set reach 4-5 tapes in size, the tapes are archived (ie. not re-used) and a fresh cycle begins with a new set of tapes (new catalog files, etc.). And so the same work that was backed up in the previous cycle doesn't just get backed up again (filling the tapes with things that have already been backed up and not changed), all work that had been previously backed up moves to a different folder (outside of "work in progress" folder) and only new jobs, or older jobs (that aren't closed/complete and moved to an archiving server for archiving on and off site) that are being revised, get put back into the "work in progress" folder to be included in the new cycle. It's a bit of work when a new cycle begins, but it prevents catalog files from getting too big (and thus becoming a huge pain to rebuild if they ever become corrupt, etc.).

 

So, that being said, since there's already a large amount of manual interaction with the tapes (rather than just requiring a large capacity that can sit in a server room and do it's thing), I don't know if an autoloader would be any benefit? The only time I could see it coming in handy would be when a second tape is required during the backup process — instead of it sitting there waiting for the tape to be changed, it's happen automatically. But, moving to LTO-4 (from AIT-2), this would happen a lot less often (and even now, with AIT-2, it happens only once a month or so).

 

Thoughts?

 

Thanks so much for your advice and experience here!

Kristin.

[rhwalker]

Sorry, thought I mentioned I only had PCI available in the G5 — and yea, I checked the data sheet and it is backwards compatible with PCI, though, I think I'd gain some performance with PCI-X (agree?).

I don't think that PCI vs. PCI-X will be a big difference here.

 

Do you think PCI would give me a performance hit? Like I said, I can get access to a G5 tower with PCI-X, it'd just take some shuffling around, so if it'd make a big difference, it'd be worth the effort.

It will make a little difference, but I doubt that it will be earthshaking. This is tape, not disk.

 

Still on this topic, is SCSI the way to go, or is SAS an option worth looking at?

Not sure I'd make that investment in such old machines. Also, since you are running Retrospect 6, you might want to check to see what is supported there. Remember, Retrospect 6 is a dead product, hasn't been developed for a few years.

 

So, I've been looking at the Tandberg LTO-4 drives. What are you opinions on full-height versus half-height? I mean, do you think it'd be the drive, even at half-height speeds, that would ever been the bottleneck?

It's probably going to be CPU bound. Really, I wouldn't put too much money into these old machines. Your money would be much better spent getting an Intel Mac.

 

 

Finally, I've been looking into the idea of the autoloader, but not sure if I'd get the benefits given the backup policy I have to work with?

Trust me, get an autoloader. It will change your life, even with a backup policy like yours. Load up both sets in the autoloader, one set with all members, the other with just the most recent members, alternate between the two, take members offsite for the second set when they fill up.

 

That way, if you forget to fool with the tape one day before you leave, alternating set backups still happen. And you always have one full set there for restores.

 

You really don't understand the value of an autoloader until you have used one. It's the only way to do tape. Really.

 

Russ

[theboyk]

It's probably going to be CPU bound. Really, I wouldn't put too much money into these old machines. Your money would be much better spent getting an Intel Mac.

 

Well, working an iMac into the budget probably wouldn't be that much of an issue, but how would you hook it up to an iMac? Even going with a StorageLoader, it's still SCSI or SAS. Would a FW to SCSI work in this kind of environment? I figured if I was going to upgrade the machine, it would have to be a Mac Pro!?

 

Oh, and I figure I should upgrade Retrospect to v8 now that v8 has been out for a while and seems stable.

 

As an aside, a while back you mentioned Retrospect has long had a dangerous bug that you reported years ago (and which was fixed in the Windows version years ago but never in the Mac version) You said the danger is caused by the interaction of one "feature" of some tape drives (or the Retrospect driver) with this particular bug — that "feature" being that Retrospect reports a tape as erased if a tape error is seen at BOT (as happens with a tape that is truly erased - no header, no logical EOT mark, etc., just blank tape). That if Retrospect needs a new tape, whether by a "new media" backup or the filling up of a tape in the autoloader, it will randomly choose what it believes to be an erased tape from within the autoloader, even if another erased tape exists in the autoloader that has been barcoded and pre-erased and pre-named using Retrospect to have the correct tape member name that Retrospect wants.

 

Do you know if this was ever resolved?

 

Thanks again for all your help!

Kristin.

[rhwalker]

There is a FireWire version of the VXA-2/VXA-3 PacketLoader drive (10 slot). Only caution there is that VXA-2/VXA-3 isn't being developed any more now that Tandberg bought Exabyte. It's a good technology, but I hesitate to start someone down the path of a dead technology.

 

I'm sure you could get a Mac Pro on eBay for very little.

 

Regarding Retrospect 8, I'd wait a couple of months. A major bugfix release is expected in the next month or two. Right now, it's a bit unstable for production use.

 

No, that "feature" was never fixed in Retrospect 6. Grumble.

 

I haven't shaken out Retrospect 8 enough to report there because it's not ready for production use. Right now, it's simply an interesting technology demonstration, and I wouldn't trust my data to it.

 

Russ

[scsctech]

If you go the SCSI route or even SAS or FC, check out overland storage. We have their 24 bay 2 drive enclosure with 12 bays and 1 drive installed. Its a fantastic unit.

Overland neo200

 

Edited February 25, 2010 by Guest