My 2 cents on some of your questions:
Can ADSM back up open files ?
A. Yes, with caveats. You get to set the rules (in the management class)
about whether or not you will accept backups of files that are open for
update. We generally do not, feeling that is better to fail the backup than
have one that is possibly invalid; however there are some sequential log
files that are fine to back up while they are open for output. And on
Windows clients, there is a problem with files that are locked. Windows can
open files for input, for update, and OPEN EXCLUSIVE. If it's opened with
the EXCLUSIVE lock, nothing can read it, including TSM or other
applications. For those files you get a message saying TSM could not back
up the file, even if you allow files to be backed up while open.
Does ADSM support data compression ? If so, What is
the compression ratio ?
A. Yes, you can set up clients to use compression. The compression ratio
will depend on the type of data. Client filesystems that have a lot of
character-based data will compress somewhere around 3 - to -1; clients where
the data is already mostly compressed (like Windows .pst files, or web
servers with .jpeg files) may not compress at all. You can find lots of
discussion of the pros and cons of client compression in the list archives
at www.adsm.org. In general, compression cuts down on the amount of traffic
you send across the network. However, it can make restores take longer
because the client has to decompress on the way back. If you have lots of
clients and you don't use client compression, your disk pool must be much
larger than if your clients don't compress. For clients like web servers
where the files don't compress well, there's no point in doing it. You can
set up each client to compress or not, as you find appropriate. You have to
make the decision based on your own requirements, where your bottlenecks
are, and your priorities. Because we backup over 400 clients, we set up
compression as the default for everyone, then address "special" cases
individually if restores become a problem. If I only had a few critical
servers to back up, I would make different choices.
And BTW, if your tape hardware compresses, data that is already compressed
on the client end, usually can't be compressed much more by the hardware.
How is security handled? Can users just recover their
own files ?
A: Clients are registered on the server and given a TSM password. You
can't recover data that belongs to another client without knowing the
password. The password is never sent over the nework in clear text.
Can labelling be done at the same time that backups
are running ?
A: Yes, but generally you don't need to; you only label the tapes once,
when you use them the first time.
Does UNIX Servers require Root or can ADSM be
configured to be fully functional from a non- root UID
?
A: Generally you run the backup (with the scheduler daemon) as root, so that
everything can be backed up. I've never tried to run the scheduler as
somebody else.
However, the client fully understands that UNIX is a multi-user system and
honors UNIX file security. There are options in the dsm.sys file where you
can put a list of the users and groups that are allowed to start the TSM GUI
client. If a non-root user is not in the list, they can't even start the
client. If they are allowed to start the client, the client honors the
standard UNIX security for file; it only allows a non-root user to back up
and restore files to which they normally would have read and write access,
respectively.
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Wanda Prather
The Johns Hopkins Applied Physics Lab
443-778-8769
wanda_prather AT jhuapl DOT edu
"Intelligence has much less practical application than you'd think" -
Scott Adams/Dilbert
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