Hi Steve,
This point has been discussed many times before,
but let try
and give you some points to bare in mind:
The 3490E catridge can hold 800Meg of data -
uncompressed.
If you send your data to the drive uncompressed
and then let
IDRC do the compression for you you should be
seeing about
2.4 + Gig of data going to the drive - ADSM will
also report it
as such. The moment you start compressing the
data before
it gets to the drive - like in the case of ADSM
client compression,
the drive is not able to compress the data any
more than it has
already and thus ADSM measures how much data is
flowing
to the drive and at the end ADSM reports 800Meg
or maybe
a little more if it was able to compress more.
You must bare in mind that there STILL is 2.4Gig
of client
data on the tape - although ADSM says + - 800Meg
was
written to tape!
It is just a matter of ADSM measuring how much
data
is flowing to tape.
Hope this has clarified the matter, if not please
let me
know.
Regards
Christo Heuër
ABSA Group
Johannesburg
South Africa
E-Mail: christoh AT absa.co DOT za
> >From: Steve Fletcher
[SMTP:SFletcher AT GIANTOFMARYLAND DOT COM]
> >Sent: Wednesday, November 12, 1997 8:54 AM
> >To: ADSM-L AT VM.MARIST DOT EDU
> >Subject: 3490E Tape Capacity
> >
> >I have a question regarding what kind of tape
capacity I should be
> >getting with 3490E tapes. We
> >are in the process of implementing ADSM for a
variety of clients
> >(Netware, NT, and several flavors
> >of Unix). I am currently backing up about 35
gigs (during the weekly
> >full backups) off of six
> >Netware servers. The data on these servers
consists of application
> >software (Lotus, Paradox,
> >WordPerfect, etc.) and the corresponding data
files for these
> >applications. The MVS server is
> >installed on an IBM 9672 CMOS processor with
EMC drives for disk pools
> >and IBM 3490 C22
> >tape drives. We are using 3490E tapes and
from what I can tell from
> >the documentation and
> >various postings on this list, I should be
getting over 2 gigabytes of
> >data on each tape. In reality, I
> >am getting less than this amount with an
average around 1.3 gigs.
> >Compression is turned off on
> >the client and it is activated on the device
class. When I turn it off
> >on the devclass, the utilization
> >drops to about 800 megs per tape.
Reclaimation is not the issue (tapes
> >less than 100 utilized)
> >since I have tapes in the storage pool which
are marked as 100%
> >utilized but containing only
> >about 1.3-1.4 gigs of data.
> >
> >I know the drives are capable of compressing
the data more, since our
> >mainframe backup system
> >from Sterling Software, is writing around 2.4
gigs per tape. This can
> >be viewed through CA1 by
> >looking at the block count and record length.
> >
> >What do I need to look at and modify to try
and get the tape
> >utilization upto expected amounts??
> >
> >Thanks!
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