Hi Stan
Some answers to your many questions, below.
tl
-----Original Message-----
From: Stan Horwitz [mailto:stan AT TEMPLE DOT EDU]
Sent: Thursday, November 14, 2002 7:35 PM
To: NETWORKER AT LISTMAIL.TEMPLE DOT EDU
Subject: [Networker] Questions about Mirapoint NMDP backups vs file
level
We are considering replacing our central email system with a Mirapoint
email server. Right now, our email server is a system that runs Tru64
Unix. The technical representatives from Mirapoint told me that they
recommend using Legato with directly attached NMDP tape drives to back up
their server (it would be about 850GB in capacity). We use standard file
level backups now with Legato 6.1.1 on a Tru64 Unix server. to back up our
existing mail server with full backups done once a week (staggered across
different volumes and tape pools) and incrementals done on the other six
days of the week.
I am finding the documentation on NMDP backups to be very sketchy. As I
understand it an NMDP backup takes a disk image and backs that up instead
of doing a file based backup. Does that mean that each day when we back up
this Mirapoint server, that it is in effect a full backup of all the data
on that system, or is the NMDP protocol smart enough to back up only
changed files?
tl> The NetWorker Administrator's Guide has a chapter on NDMP that does a
good job of summarizing the basics; if you want more, check out
http://www.ndmp.org/ for more NDMP information, history, etc, as well as
several Legato white papers on the subject. NDMP does not require that a
disk image be created for backup use. There are some file server
implementations (EMC IP4700, for one) that support the (optional) creation
of a snapshot of the disk to be backed up, after which the backup occurs
from the non-changing snapshot (a very good idea, IMHO). But this is not a
NDMP requirement. NetWorker's NDMP implementation supports both full and
non-full (differential) backups. But it's important to remember that,
though NDMP is a standard, the actual backup program that is run in the NDMP
device is NOT 'standard'. In fact, there are no standards for these
embedded backup programs, except that they need to use NDMP to converse with
backup servers. So, you need to read the fine print describing Mirapoint's
backup program to understand if it supports, for instance, snapshots or full
and non-full backups.
If this NMDP protocol does a disk image backup, how does one restore a
single file? For example, how would we get back a four month old log file
if it is needed for a legal investigation?
tl> Since that depends entirely on the capabilities of Mirapoint's backup
program, seek answers from them.
Can these Mirapoint NMDP files be restored to a regular Unix system, or
must they be restored back to a Mirapoint system? I would think so since
Mirapoint's OS is based on BSD Unix.
tl> In general, I'd always plan to restore data back to the same
environment from which it came. If Mirapoint supports restoring to other
environments, then that's even better.
Is it realistic to expect to bring in this Mirapoint server with our
existing tape library? We would add additional tape drives to it in order
to use with a direct connection of those drives to a Mirapoint server.
tl> I believe that it is. And you have many options. One would be to
directly connect (via SCSI) one or more tape drives in your tape library to
the Mirapoint system, and have the tape library's robotic device and other
tape drives connected to one or more other systems; this works fine with
NetWorker. You could also connect your Mirapoint system to a storage area
network (if Mirapoint supports this) and use NetWorker's Dynamic Device
Sharing facility (which also supports NDMP) to 'move' your tape drives among
the systems that need them. That also, in my testing, works fine; there are
some limitations, which are covered in the documentation.
We also plan to migrate our Legato server to a Solaris server fairly soon.
I hear that Solaris is a better platform for our backup server needs than
Tru64 Unix. We actually have the new server on-site, but we are waiting
for delivery of a few small components to go with it.
tl> As you probably know, NetWorker Server for Tru64 does not support NDMP.
So you will have to change your NetWorker Server platform in order to
control NDMP backups. Using NetWorker on Solaris is always a safe bet, as
that is the reference platform (Legato does their NetWorker development on
Solaris first, then ports it to other operating systems, I believe).
If anyone on this list has any experience on using a Legato server to back
up a Mirapoint system, please let me know what your experiences are.
tl> I have no experience with this. But I'm very encouraged to find that
Legato already lists Mirapoint in the current Legato Corporate Price List as
well as the current Legato Software Compatibility Guide. So, you can be
assured of Legato's support as you move forward. I'd also ask Mirapoint for
a manual or white paper that specifically describes how to configure and
manage backups of their product using NetWorker software. Any company that
is knowledgeable and serious about providing backup solutions to their
customers does this (see http://www.emc.com/techlib/ for an example).
tl> Hope this helps, and please let us know of your odyssey!
Thank you,
Stan Horwitz
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