Hi,
We are currently evaluating a network appliance solution for our site.
We still have deep concerns about our abilities to backup such vast quantities of data from one source and even greater concerns on our ability to restore such vast quantities of data in the event of a disaster within a feasable time frame.
I would like to hear from people about how they backup their systems - i.e.:
What backup software do you use?
A cron job on an admin host kicks off a full-filer dump on each of our erm 9-going-on-10 filers using rsh and loggid the output to backups-logs.
What size is your file server and what size are the partitions?
Ranging from piddly 50GB ones to reasonably meaty 200MB.
Is the tape directly connected to the file server or do you backup via the network?
We have 4 Exabyte stackers, 3 DLT4700's and a single DLT4000 all directly attached to filers. When there's a tape drive problem (infrequent but hey they involve lots of moving parts) we get a little downtime during lunch or beginning/end of business and perform a quick halt-detach-reboot cycle, work on the drive while providing service, then do a halt-attach-reboot to bring it back together. Sometimes this stalls a lot of machines and it'd be ideal if we didn't have to do it but pretty much everything recovers, though we have to get brutal with locks the filer wishes to honour after reboot when in actual fact the client has just gone awol and won't talk to the filer about the lock...
If you backup via the network, how is your file server interfaced to the network (dedicated backup network(s)? - 10/100 Mb/s?)
We've considered the option but we'd need a dedicated LAN to get the performance and avoid loading the production network on the basis that we do serve sites around the world.
Do you use ndmp?
Still waiting for it to mature and appear in products we feel happy to use and rely upon.
How many streams of backup do you use in parallel?
One per filer, cos we've only *currently* got one device on each filer.
What speed/rate do you backup (GB/Hr) per drive?
About 2.3MB/sec. (I reduced the numbers to that dimension and can't recall what they were in GB/hr - I'm sure you can work them out).
Do you utilize more than one tape drive for backups?
One drive per box though we're looking at two or more per box in future.
Have you needed to restore a file system?
Sadly yes, way back a year or so ago on an older box on an older release of the software we suffered a catastrophic loss of a box. It took me a long time to restore the bits we needed because I was, at the time, reduced to using ufs_restore from a Sun over the network. Still managed 1MB/sec though. Otherwise I just smugly cp things out of snapshots.
If so, how long did it take you (GB/Hr) ?
Days.
Were you able to retore in parallel streams?
Nope.
Since the list of questions came out long, I will be more than happy to call you and poll you verbally on the above (send me your number). I will even be more than happy to post the statistical results of those willing to participate.
I hope people chip in - it'll be interesting to see if backups on filers has become customer-target no 1, now that there're so many good things in DOT5 to play with.