Re: Linux+RAID+backup?

[David Monro <davidm amberdata demon co uk>]

> Hello everyone,
>  
> What suggestions do you have for backing up RAID disks attached on 
> a PC running Linux?
>  
[stuff removed]
> We attempted to backup the RAID attached on the newly purchased 
> Linux box, over the network to our Sun backup server, but the 
> throughput was very slow.  We are now thinking of purchasing 
> a new tape drive and directly attach it to the Linux box.  

This is odd - depending on the Exabyte (and network) you are using, your
network should probably be faster than your tape drive (eg my 8700 can stream
at between 500k/s and 1M/s, and you should be getting near 1M/s on ordinary old
ethernet). How are you actually running the backup - using tar over nfs or
something? I would suggest have the sun box do something like 'rsh linuxbox
"/sbin/dump 0f - /thefilesystem"' - this used to work nicely for me when
running the backups at my last job. Either that or you have a rather faster
tape drive than I do :-)

>  
> * Has anyone done this?
> * I would appreciate suggestions on how to backup our new RAID disk.
>  
> Specifications:
>    Intel Celeron (Gateway) RedHat Linux 2.2.5-15
>    Arena IDERAID5-84 with 32bit PCI Ultra-Wide SCSI
>    (will we have to get another SCSI card to attach an 8mm Exabyte
>     tape drive to the PC?)

If you do go the separate Exabyte route, it very much depends on how many
devices and what cabling you have available for the SCSI card. On the other
hand you should be able to pick up an ncr53c810 card which will do the job
nicely for not very much. I've no idea what the Arena IDERAID5-84 is so I can't
really comment on that one.

Another possibility would be to upgrade the network between the two machines in
question - given the rather excessive cost of Exabyte drives it might come out
cheaper.

Either way, I'd probably use 'dump' as the backup software assuming you are
using extfs file systems (not sure if it comes as part of redhat; I use debian
and it comes with it). Syntax and even output file format is very similar to
commercial unix versions (since they are probably all derived from the same
Version 6 AT&T unix source - they all had the same rather subtle (and almost
completely harmless) bug when I looked a couple of years ago regarding
restoring files with a hole at the end).

	David