Tim,
Actually, two different behaviors based on two-different problems. Files
that start less then 2 GB but grow > 2 GB will continue to use subfile
backup as long as the other requirements for the base file (i.e., the file
on the client cache) is still valid. The limiting factor here is that
there is only 32-bit support in the differencing subsystem that we are
using. We chose 2 GB on the onset (instead of 4 GB) as the limit to avoid
any possible boundary problems near the 32-bit addressing limit and also
because this technology was aimed at the mobile market (read: who is going
to have files on their laptops > 2 GB). I understand that there are
several shops that use this technology beyond the laptop environment.
Ultimately, the solution is to have a 64-bit subsystem in place so that we
can go beyond 4 GB. I suggest a requirement to Tivoli if this is
important to your shop.
The low-end limit (1024 bytes) was due to some strange behavior with
really small files, e.g., if a file started out at 5 k and then was
truncated to 8 bytes. The solution was to just send the entire file if
the file fell below the 1k threshold. We can get away with resending
these small files because ... they are small files! It is probably a wash
to resend or to try to correctly send a delta file in this case.
Hope this helps.
- Jim
J.P. (Jim) Smith
TSM Client Development
smithjp AT us.ibm DOT com
Thanks Jim!
I was confusing "size of base file falls < 1024" with 1 GB!
So if a file starts at less than 2 GB but then grows bigger than 2GB it
will
no longer be eligible? Similar if a file falls below 1024 bytes?
Thanks again!
Tim
-----Original Message-----
From: Jim Smith [mailto:smithjp AT US.IBM DOT COM]
Sent: January 3, 2003 4:36 PM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: Sub-File Backup - 1 GB Limit
Tim,
Actually, the subfile limit is 2 Gig; if a file size > 2 Gig then TSM will
not bother to copy the base file to the client cache, so it could not be a
candidate for subfile processing on a subsequent backup.
Thanks,
Jim
J.P. (Jim) Smith
TSM Client Development
smithjp AT us.ibm DOT com
Last August, Jim Smith wrote:
>Today the client code will send a new base file in these cases:
>
>- if the last time the detla was taken, the ratio of delta:base is > .40
>- digital signature of base is incorrect or doesn't match signature on
>server
>- base entry on client cache is dirty, i.e., never committed on the
server
>- size of base file falls < 1024
>- file is excluded from subfile backup processing, i..e, exclude.subfile
>- file is encrypted by Windows efs
I just want to double check, does this mean that there is still the 1GB
limit for subfile backup? Ie. If a file is > 1 GB, is it ineligible for
subfile processing?
Thanks,
Tim Rushforth
City of Winnipeg
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