[comp.sys.dec] Sharing a common BACKUP device with UNIX nodes.....

sinclair@aerospace.aero.org (William S. Sinclair) (05/18/89)

Is there an arrangement similar to Local Area Vax Clustering for UNIX
devices,in particular DECstation 3100's? We have 4 or 5 of the little
nippers, each with 330 MB of local disk space. We would like to buy a
single file backup device, then have all of them share it, so that a
nightly backup of all the UNIX nodes can be done with a minimum of
headaches. Assuming that node #1 has the backup device on it, then nodes
#2, #3, #4, etc. would then be NFS servers in turn, where node #1 is the
client. But that seems like a cumbersome arrangement. Maybe something
more reliable is possible. I know that SUN networks can do it; they use
the EXABYTE video cartridges, but I don't know about DECstations.

steve@fnord.umiacs.umd.edu (Steven D. Miller) (05/18/89)

To the best of my knowledge, Sun networks certainly *can't* cluster to do
dumps, at least not in the way you're describing.  Dump can't work over NFS,
for one thing; it needs access to the raw disk device, and NFS doesn't
provide that.  It is possible to cobble something together so that the
machine with the tape rshes out and dumps the others to its tape.  Heck,
Sun doesn't even support (i.e., sell and maintain) Exabyte tape units.

Of course, if you know something different, and can post details, I'd
like to hear them...

	-Steve


Spoken: Steve Miller    Domain: steve@mimsy.umd.edu    UUCP: uunet!mimsy!steve
Phone: +1-301-454-1808  USPS: UMIACS, Univ. of Maryland, College Park, MD 20742

cetron@wasatch.utah.edu (Edward J Cetron) (05/21/89)

	While there is no LAVC style common backup technique, you can 
accomplish the same task via RDUMP/RRESTORE  which simply allow you to
run DUMP/RESTORE over the network (tcp/ip rxxx style) to a tape/disk on a
remote node.  I am pretty sure ultrix supports it (it supports rwho, ruptime,
and rlogin...).  We've used it often when our TU77 would crap out.  Speeds
over the ether from a 750 to an 8600 with/ Tu78's was roughly equivalent
to the local TU79 (bottleneck was CPU anyway).

-ed
cetron@wasatch.utah.edu

jparnas@arnor.UUCP (Jacob Parnas) (05/22/89)

In article <17585@mimsy.UUCP> steve@fnord.umiacs.umd.edu (Steven D. Miller) writes:
>To the best of my knowledge, Sun networks certainly *can't* cluster to do
>dumps, at least not in the way you're describing...  

>Sun doesn't even support (i.e., sell and maintain) Exabyte tape units.
 
>Of course, if you know something different, and can post details, I'd
>like to hear them...

We use rdump to back up 30-40 RTs and Suns on our network using one Exabyte
tape drive with the driver supported by Delta Microsystems.  We get about 
180 kilobytes per second over the network using dump/rdump.  Sun does have
a driver for the Exabyte tape unit, but it is not as fast as the Delta
Microsystems one.

>
>	-Steve
>
>
>Spoken: Steve Miller    Domain: steve@mimsy.umd.edu    UUCP: uunet!mimsy!steve
>Phone: +1-301-454-1808  USPS: UMIACS, Univ. of Maryland, College Park, MD 20742

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elgie@canisius.UUCP (Bill Elgie) (05/22/89)

In article <31427@sri-unix.SRI.COM>, steve@fnord.umiacs.umd.edu (Steven D. Miller) writes:
> To the best of my knowledge, Sun networks certainly *can't* cluster to do
> dumps, at least not in the way you're describing.  Dump can't work over NFS,
> for one thing; it needs access to the raw disk device, and NFS doesn't
> provide that.....

  I may be missing something here (like a qualifier).  But we run rdump bet-
  ween Microvax IIs and a MIPS M/120 (via NFS) with no problems...

  greg pavlov (under borrowed account), fstrf, amherst, ny

steve@fnord.umiacs.umd.edu (Steven D. Miller) (05/22/89)

What exactly do you say when you do the dump?  Dump should need to go
through the raw filesystem; at least, any dump program I've ever seen
(tar and cpio don't count) has used the raw filesystem.  I'm not saying
that you can't do a rdump from a machine (whose filesystems you may have
mounted via NFS) to a tape drive somewhere else... but if someone is actually
using NFS to read the files for the dump, I will be mightily surprised.

	-Steve


Spoken: Steve Miller    Domain: steve@mimsy.umd.edu    UUCP: uunet!mimsy!steve
Phone: +1-301-454-1808  USPS: UMIACS, Univ. of Maryland, College Park, MD 20742