Yes, files larger than 2 GB are backed up individually when you have subfile
backup turned on.

However (don't shoot the messenger here), I'll save you some time and
confusion by pointing out that you aren't going to get any significant
benefit from implementing subfile on a large file server.

Subfile backup was designed to work on laptops, not servers.

The "base" or initial backup copy of a file is stored in a cache directory
on the client, which is also limited in size to 2 GB.  TSM uses the base
file to calculate the changes or "delta", and sends the delta only (the
subfile) on subsequent backups.

But once  you exceed 2 GB of backed up files in the cache, older files (LRU)
are purged from the cache.  When they change and need to be backed up
again, it is a regular backup, not a subfile.

In short, you can only manage a total of about 2 GB of files for subfile
backup, and only files less than 2 GB in size are eligible.


On 2/13/08, Sam Sheppard <SHS AT sddpc.sannet DOT gov> wrote:e
>
> ---------------------------- Top of message ----------------------------
> >>--> 02-13-08  16:06  S.SHEPPARD     (SHS)    Re: Backing up PST files
>
> We are in the same boat here but, even worse, the customer has 'chosen'
> to store all of the .PST files on a shared NetApp FAS drive, something
> not officially supported by Microsoft. Supposedly this was only going to
> be a temporary solution until implementation of something called
> Symantec Enterprise Vault. However, the $1M price tag on that is now
> a problem and we have been asked the implications of continuing to do
> these backups as we do now, given a 1TB/year growth rate.
>
> Currently, we are backing up around 400GB/night out of 2TB of .PSTs and
> were going to setup a test of subfile backup early next week.  I too
> would be interested in any limitations to this scheme.  If there is a
> .PST larger than 2GB, is it backed up normally?
>
> Thanks
> Sam Sheppard
> San Diego Data Processing Corp.
> (858)-581-9668
> -----------------------------------------------------------------------`
>
>
> ---------------------------- Top of message ----------------------------
> >>--> 02-13-08  10:43  ..NETMAIL     (001)     [ADSM-L] Backing up PST f
> Date: Wed, 13 Feb 2008 12:41:56 -0500
> From: "Paul Zarnowski" <psz1 AT CORNELL DOT EDU>
> Subject: [ADSM-L] Backing up PST files using dynamic subfile and OFS
> To: ADSM-L AT VM.MARIST DOT EDU
>
> _________________________________Top_of_Message_________________________________
>
> Greetings...
>
> We are starting to use Exchange and Outlook here, and now we need to
> figure
> out how to backup PST files..  I know there has been some discussion of
> this in the past on this list, and I have researched this.  Here's our
> problem.
>
> We have a client constituency who will be running Outlook on systems, some
> of which are connected sporadically (laptops) and/or over slower speed
> network connections.
>
> It seems that Open File Support (OFS) can be used to successfully back up
> PST files, which is good.  We'd like to also use dynamic subfile backup on
> the systems that are connected via slower networks.   The problem is that
> subfile backups have a 2GB filesize limit, and PST files can grow
> >2GB.  Is
> anyone else faced with this challenge?  If so, how are you addressing it?
>
> Thanks.
> ..Paul
>
>
> --
> Paul Zarnowski                            Ph: 607-255-4757
> Manager, Storage Services                 Fx: 607-255-8521
> 719 Rhodes Hall, Ithaca, NY 14853-3801    Em: psz1 AT cornell DOT edu
>
> -----------------------------------------------------------------------`
>