Re: Linux+RAID+backup?

["Wes Bauske" <wsb paralleldata com>]

David Monro wrote:
> 
> > 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 :-)
> 

I use rsh and have no troubles saturating my Eliant/DLT4000/DLT7000
using 100Mb Enet. So it works if you have reasonable networking.
I can also run between my AIX boxes and Linux without trouble.

Keep in mind older Exabytes only go 250-500KB/sec. Eliants go from
500-1500KB/sec, and the new ones are around 2-3MB/sec, assuming you
use the new tapes. (assumes no compression since my data doesn't
compress)

> >
> > * 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?)
> 

Just to be clear. This is an Alpha Linux list, not Intel but your
question is relevant on Alpha's also. 
Why are you using the term IDE and SCSI in the same sentence? 
They're different technologies. If you have IDE disks, you'll 
need a SCSI card to attach an Exabyte, at least I've never 
seen an IDE Exabyte.

> 
> 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).

dump comes with RH6.0 also. Use whatever you've been using if
it does the job for you. With Intel Linux you also have other
choices if you get the boxed version. And, whatever you do,
try to keep your tape block sizes reasonably large, 10KB or
more. My preference is at least 64KB.


Wes