A lot of what you need to look at is the type of data you are backing
up.
From what I have been told and read is that 3490 drives will only hold
1.2GB
of uncompressed data. It sounds like you are getting some compression,
just not much. If the files you are backing up are binary files and not
text you
probably won't get much compression.
Mark A. Adams
UNIX SYSTEMS ADMINISTRATOR
(402) 963-7369 Office
(402) 444-0754 Pager
Communications Marketing Services
SITEL Corporation
7444 Farnam
Omaha, NE 68114
>-----Original Message-----
>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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