| Title: | MAGNETIC TAPEDRIVES |
| Moderator: | STKHLM::GJOHNSSON |
| Created: | Mon Sep 21 1987 |
| Last Modified: | Fri Jun 06 1997 |
| Last Successful Update: | Fri Jun 06 1997 |
| Number of topics: | 3775 |
| Total number of notes: | 13147 |
I've just installed Networker 4.3 on an Alpha NT 4.0 system, with a TLZ07 DAT drive. It seems I can only get 4 GB on each 120m tape. So I tried using plain NT Backup. (Service pak 1 applied) Looking at Explorer properties the server uses a total of 11910 MB diskspace. I've backed up the server twice. First using standard NT Backup, no compression. Four tapes needed (4039+4016+4017+732 MB). Using hardware compression from the NT backup screen I get 4240 and 4239 on the first two tapes, haven't finished the third one yet... So why can't I get 8 MB on a tape? Revision of the drive says 4BE0, using a 4mmdat.sys dated 1996-08-02, size 18KB, that came with the NT 4.0 upgrade I guess. Rgds, Hans
| T.R | Title | User | Personal Name | Date | Lines |
|---|---|---|---|---|---|
| 3699.1 | LEFTY::CWILLIAMS | CD or not CD, that's the question | Thu Mar 20 1997 01:26 | 18 | |
What exactly is the data?
The TLZ07 is rated at 4GB uncompressed capacity. If the data is
compressible, then you can get more with compression. Typical
commpression ratios, with "normal" data sets, tend to average 1.5 to
2 x, giving capacities of ~6-8GB.
If the data is already compressed, running with compression on will not
give you any extra capacity over uncompressed, and may actually
decrease the capacity - recompressing the data can expand it in some
cases.
It's still possible that compression is not being turned on somehow,
but NT backup is usually a good indicator - if it lets you turn it on
in the menu, it is turned on.
Chris
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