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strategy for disk-to-disk-to-tape backup

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I have a G5 xServe with an xServe RAID attached (via fiberchannel). I back up approximately 120-130 computers (half a dozen Windows boxes, the rest are Mac OS X) to the xServe RAID.


I also have an Exabyte Magnum 1x7 tape drive hooked up to the xServe (via SCSI).


Ideally, I would like a disk-to-disk-to-tape solution where the server backs up clients on the RAID for a set period of time (not yet determined), then the data from the RAID gets copied to tape (undoubtedly multiple tapes). I would want to keep the most recent set on RAID and then when I move on to the next backup set, copy the last one to tape(s). Would this be using Retrospect to copy the existing Retrospect data (on the RAID) to tape, or would I need to use dd or tar for that?


If someone could offer advice I would appreciate it.

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Welcome to the Retrospect backwater where development has passed by without notice ... in other words, in spite of the number of other packages that do this out of the box, Retrospect still can't in any meaningful way !


I have tried to simulate this in the past without too much success. Here's a few tips :


You can set up a Duplicate operation to update the local disk to be an exact copy of the client. You cannot do this in Backup Server mode, only on a timed schedule basis (so if the client isn't on at the scheduled time, it doesn't get done).


You cannot do this with a Windows client to a Mac server as important file information will be lost. To do Windows cients you need to duplicate to a Windows disk - I suspect you can do this to a Windows client with a Mac server but I haven't tried. When I was doing it, I had an old Windows server and a spare Retrospect licence so set that up separately to my main backup server.


The useful feature that eliminates duplicates (ie doesn't copy the contents of a file, just information that it's there, if the same file has already been copied into the archive) doesn't work within a source. So whilst the space used for a lot of application and system files is saved when copying them individually, this doesn't happen when copying your intermediate backup - thus enlarging your archive media requirements.


You can get around this by backing up the intermediate store subvolume by subvolume - but this then makes even more work.



Where I did find the technique useful, but ultimately too much administration, was to reduce the effect on clients of the first backup to a recycled archive. By having a local disk with a fairly up to date copy of a client, I could backup that first - with the result that when the client itself is backed up, most of the files on it are already in the archive and so don't need to be copied.

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ouch. not what I wanted to hear!


I'm now moving on to another strategy: duplicate each individual's home directory to the RAID volume on the xServe, then use a typical Retrospect backup to move all of that data to tape. On the minus side, this only gets user data, no system or application info. However, given that any sort of drastic restore (due to equipment failure or whatever) would involve a machine with a new system image, I don't really care. My users don't have access to write to the system-level /Applications or /Library directories, so there's nothing there that can't be more easily recreated than restored.


However, I now find myself having to create hundreds of duplicate scripts, one for each volume, because it doesn't seem that "Duplicate" can handle subvolumes on multiple clients.


Any suggestions?

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BRU (Tolis Group) does have disk-to-disk-to-tape ("d2d2t"), but there are some features of Retrospect that BRU doesn't have, and the interface, while now GUI rather than command line, isn't something that my secretary could use to retrieve files, as can be done from Retrospect. I evaluated BRU but chose to stay with Retrospect. I would expect that the next version of Retrospect for Macintosh will have d2d2t because the Windows version has had this feature for a long time.


Have you considered using Portable Home Directories or Network Homes for your Mac clients so that the home directories are on the Xserve? That's what we do. Then you could just use unix command line tools to copy those homes (/User/*) to a repository to get backed up.



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Portable home directories or network homes won't work for my laptop users (~35 of them), nor the users inside my department but outside of my building (another 15 or so).


I guess I have to be patient until Retrospect for Mac moves into the 21st century. You'd think (!) that EMC would remember that Retrospect originated on the Mac. I guess not...


In the meantime, I've created a bazillion backup servers, and on each client volume have defined a subvolume of /Users that will be backed up (using Retro) to the xserve. From there I will use Retro again to back up that data to the tape drive. It would mean a two-step restore process, but hopefully not much more trouble than that.

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