NetNews Usenet Archive 1992 #18/NN_1992_18.iso/spool/comp/unix/ultrix/6381

Internet Message Format | 1992-08-20 | 8.9 KB

Path: sparky!uunet!elroy.jpl.nasa.gov!usc!rpi!uwm.edu!ogicse!usenet.coe.montana.edu!osyjm
From: [e-mail] (Jaye Mathisen)
Newsgroups: comp.unix.ultrix
Subject: Re: DECnsr, has anyone any experience with it?
Message-ID: <[e-mail]>
Date: 19 Aug 92 22:47:12 GMT
Article-I.D.: coe.1992Aug19.224712.27925
References: <[e-mail]>
Sender: [e-mail] (USENET News System)
Organization: CS
Lines: 174

In article <[e-mail]> [e-mail] (John Stoffel) writes:
>
>Our site is looking into getting DECnrs, the Network Save and Restore
>system for our Network of DS3100s and 5000s.  Has anyone out there had
>any experience using this product?  If so, could you answer some or
>all of the following questions?  Any other Backup and Restore programs
>or philosophies or even anecdotes would be very appreciated.  Thanks!

Be happy to... (Be warned, critical commentary on a DEC product ahead).


>What problems did you have during installation and configuration?

None.  It installed easily.  Configuration is easy if you ignore the
idiotic curses interface, and just use 'edit' from the nsradmin> prompt.
You can block copy stuff right and left (remember to remove the
resource ID gunk), and basically whip it out.

One note, after you delete a resource, save it, let NSR update its databases,
then re-edit and make more changes.  If you don't you can get into situations
that have inter-dependencies, where your only recourse is to exit w/o saving
your additions.  Of course, careful planning will help...
>
>What backup medium are you using?

2 CCG 8mm's (8200's), probably switching to 2 TLZ06's.

>How much disk space are you backing up, and how much space did the
>online file indexes use?

12-14 GB's.  The indexes are a big problem... more later.

>Was it easy to use?  Easy to add/delete partitions from the list of
>disks to backup?  Easy for users to ask for old files to be restored?

all things considered, yes.  yes.  yes.



The biggest problem is the file indices.  You can get into situations where
the file index is so large, that NSR can't scavenge records from the old
database, because their isn't enough disk space.

I had 2 weeks worth of backups, 20 tapes, 6-7 clients, and it consumed
all of an RZ25.  (about 3.5 MB's left).  Now, I wanted to nsrck the indices,
but 3.5 MB's isn't enough space, so the admin has to clear out 500 MB's of
disk somewhere else, copy the old db to the new space, make a symlink to
point to the new database, run the nsrck, then copy it all back.

I want to keep 3 months worth of indices and tapes on-line.  That'll be
about 1.3-1.4 GB's.  Ultrix can't handle stripe sets or any disk large than
2 GB's, so I can't rebuild this index file if I need to.  Major boner.

Get the fastest disks you can to keep the index files on.  I deleted a volume
from the media database, and purged all the file index entries for that
tape, it took 2.5 HOURS...  on an RZ25.  If you ever wanted to purge a bunch
of tapes, you'd be better off to delete nsr, reinstall it, and rescan the
tapes you want to keep with scanner.

A nsrck of a 240 MB index file took 11 hours on an RZ56, on a machine that
was otherwise unloaded.  This seems extraordinary.

Bitches:

Doesn't support HP9000/700 series.  Even after 2 releases.  They support
300's and 400's, but who cares about them?  How hard can it be to re-compile?
I think DEC is chicken...  don't give 'em any reason to buy the competitor...

Big bitch and moan:
Licensing is bizarre.  My license expired for nsr, and now the nsr daemon
won't start... Understandable...  How the hell am I supposed to recover
files 2 years from now when I decide to use HP Omniback and not NSR?  I have
to keep an active license for a product I won't use?

It may be possible to use scanner and the uasm modules to restore from the
expired tapes, I haven't had a chance to try it, but even if it works, it's
beside the point.  I can't use recover to get the data back, and browse the
tapes looking for files, ...  Seems to me a more reasonable restriction would
be that w/o a valid license, saves won't start, but recovers will work.  This
is probably what will keep me from purchasing it again.  I'll use amanda before
this...

When using mm to delete a volume, the mm command eventually returns, giving
you reason to believe that the volume info has been purged, but it's not,
it's still running in the background.  But you don't know this, you do
another mm -d, and now you've got two of them, and your nsr disk is going
bonkers, ...  it's a nightmare.  To be fair, the "extra" nsrindexd's are
just hanging around waiting, they run in sequence, not in parallel...

No easy way to tell which file systems are backed up at which times, w/o
following through a bunch of junk, ie, first, find the client that has
the file system you want, then find which group it's in, then find that
group specification, then find the time.  Pain.  It might be possible to
give a query from the nsradmin prompt that would do this for you, but it
didn't look trivial.  A simple tool that would generate a calendar for a month
or week that has the schedule of clients/groups for quick perusal would
be nice.

Requires that the server machine be in the clients /.rhosts to start up
remote saves.  I had hoped for a more sophisticated mechanism... Seems
like it's opening up the client w/o a real good reason... why not incorporate
some new authorization technology into this thing?

It's based on Sun RPC, rather than OSF technologies...  Perhaps DEC is
only paying lip service to incorporating OSF DCE technology...

NSR provides a mechanism for specifying how many parallel saves will be
done at once.  Don't believe it.  It says 4 is the default, and it looks like
4, but I've seen 8 at a time all trying to run.  Buries the server.

NSR's got memory leaks, and it's a major memory hog... my daemon reached 13MB's
 of real RAM in size.  The server is a 5000/240 w 48MB's of RAM, and during
backups, the free RAM drops to 2-3 MB's.

I did not get a chance to test 1.1, perhaps some of these problems are fixed.

No Motif interface... It would be nice to be able to just point and click
your way through, but doesn't happen.

The monitoring software is based on curses, and gets easily confused about
what to display.  It has a screen that's divided into several areas, and
has it's own ideas about how they should be sized.  You have to make the
window pretty large to get all 8 sessions that might be running at once to
be displayed, but it grows the "message" area way out of proportion.  Then
it prints 6 copies of the status messages to the message area, scrolling
the useful info off too fast anyway.  (Not all messages, just (Info) messages
seem to get multiple copies, and fast).  The curses interface also gets
confused, it will show a backup in progress in the "current sessions"
area, but won't show it in the message area, and if you resize the window,
then the message will go away.

NSR doesn't support many devices... None of the SCSI TF devices, no
8mm 8500's, no TLZ06 support in compression mode.  NSR can't stream
both drives at once, it fills one, then starts the other.

You can't specify where you want file systems to go, ie, Full backups
on one tape devices, incrementals on the other.

It's tough to make off-site storage tapes, ie, I want to make a tape
that has all the user files systems backed up, and gets put in a vault, but
doesn't become a part of the regular backup indices.  You can't do this.
What you have to do is empty and dismount your tape drives.  Disable all
the groups so that there's no chance of an automatic backupstarting, then
init and label a new tape, do your backup, the delete the volume and
file index entries from the media database, renable the groups, load up
the old tapes, and check that you didn't miss any scheduled backups.
Pain in the butt.

Over all, I'd give it a grade of B-, it's better than dump/restore, but
has some major pain-in-the-butt areas that need polish.

Would I buy it again?  Doubtful.  I've chatted with people who have some
of the other enterprise backup solutions, and they don't report having
any experiences like this.

Minor side note to EDU people: NSR isn't under CSLG/TEI stuff yet, although
it's a dec-developed product.  It's not outrageously expensive, but it
ain't cheap either.  With my luck, it'll go under CSLG 2 days after I buy
something else.

Am I too critical?  Too picky?  I don't know.  Some of these problems seem
very obvious... Rumor has it that DEC's been using NSR internally
for quite some time.  I hope their license never expires :)...

To DEC's credit, they've been helpful in answering questions, even if
most of the answers have been, "you can't do that."

If you have questions or commentary, feel free to mail...

(NSR is kind of like DEC's VXT2000 X terminals.  So darn close, yet so far)...
--
 Jaye Mathisen, COE Systems Manager                [phone]
 410 Roberts Hall,Dept. of Computer Science
 Montana State University,Bozeman MT 59717    [e-mail]