[ILUG] Re: backup questions (long, semi OT)

[John P . Looney]

On Tue, Oct 26, 1999 at 05:49:06PM +0100, Jakma, Paul mentioned:
> >  I've been using Legato Networker for a good while. For really big
> >  systems, it's smashing. OK it has problems, but in complex situations,
> >  it does work.
> what kind of problems exactly? and what are the recovery options like?
> (also, what's the price like?)

 Well, stuff like indexes periodically get corrupted, disks fail and you
lose indexes (which have to be read back off tape - takes hours). But,
compared to others I've seen, it's a good system. It stores a list of every
file & tape & machine it's ever seen (you can tell it to forget
tapes/machines/files after a year or two years or whatever).

 When you want to backup, you make a save set, which could be "These ten
machines, full backups on a friday, incrementals everyday". You then
"enable" that save set - and it works automagically from then on. It'll
handle "cloning" tapes & stuff, if you want to keep a copy of a backup in
the jukebox, and a copy of the backup off site. Their are very useable GUI
and command line tools.

 Recovery is a bit cool. You can browse all the backups of all the machines
that you've backed up. You can select the specific backup you want, and if
it's a full+two incrementals, it'll just say "This requires seven tapes,
two of which are off site, one is in the jukebox, and the others are in the
tape room, the tape numbers are: blah blah" etc. You get all those tapes,
and tell it to go ahead. Simple. For those that don't know how it knows the
tape numbers, it can control a tape library, with a robot arm that has a
bar code reader on it. So, you can load a library up with a few hundred
DLT's, the robot arm will scan them in, give networker a list of tapes, and
networker will know they are all blank, and can be used for whatever
backups it wants to use them for. You can set "recycle times" on tapes too,
so that periodically a clone is made, ejected from the jukebox, and the
incremental backup tape is reused.

 Recovery is simple, unless of course, one of the tapes is corrupted. You
are supposed to be able to mark a tape as "suspect", and then when you try
and read from that tape in future, it'll look for the clone of that tape
instead. Doesn't always work though :(

 Price ? List is about £5000 for a Unix server license, about £1200 for an
NT pack, £900 for a database backup license, and about £900 for a client
license - though you get 10 client licenses with the £5000 server license.
Of course, they do decent discounts too :)

 AFAIK, they don't do a Linux server yet. You never know though!

> > you can have a look around. Though it's a bit heavyweight if you don't
> > have a jukebox or two to backup to.
> Good point, anyone know how good the support in linux is for Tape
> changers/libraries/silo's? Specifically the kind of things that have
> multiple scsi id's, eg Compaq 20/40 DLT library. (which some say looks
> suspiciously like a quantum).

 It's only really for use with Tape Libraries. "nsrjb" supports about
thirty different jukeboxes. I've only used it on big storagetek boxes
(these things have six DLT drives, and between fifty and four hundred
slots! They do paralellism, so if a machine has multiple filesystems, it
can backup as many as you want at the same time. If you set the paralellism
to twenty, it can (say) take five streams off four machines at the same
time, and be writing multiple streams to a single tape. Why it lets you do
this, I don't know. But you can :) Apparently, it's handy if you have
multiple gigabit ethernet channels coming into a single backup server, and
seeing as a single gigabit ethernet pipe is still a bit narrower than
mulitple U2W SCSI pipes...

 Enough info ?

Kate

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