On Thu, 8 Dec 1994 15:10:26 CST Larry Sanders, VM System Maintenance said:
>On Thu, 8 Dec 1994 11:50:19 CST Keith A. Crabb said:
>>I have Memorex equivalents of 3490E tape drives and am using the 3490
>>extended length cartridges with data compression on the clients and am
>>seeing about 800M per cartridge.  So I'd say 400M is about what you would
>>expect from standard length cartridges.  You can store more on the tapes
>>without data compression on the clients if you're willing to pay the
>>network bandwith though.  In tests I got about 1200-1400M on a 3490
>>extended cartridge but, we decided to just buy more tapes rather than
>>pay the extra 30-50% of network traffic during a backup/restore.
>It's true that if you turn off data compression on the clients, the ADSM
>server will report that it is putting more data on each cartridge, but
>that is because the server would be writing uncompressed data instead of
>compressed data.  Regardless of whether data compression is being done
>on the client or by IDRC, it is still the same amount of data, and should
>require about the same number of cartridges.

Oh, I thought that hardware compression was still generally from 5-20%
better than software compression, depending on the scheme used.  We had
figured who cares if we have to buy 20% more cartridges to store data,
it would take a lot of cartridges to equal even one 10baseT hub.  If the
data storage is really about the same, I quess we shouldn't have bothered
worrying about it.  Alas, live and learn.  Fortunately the decision was
driven by network load or I guess I would be much embarrassed.

---
Keith A. Crabb         Keith AT UH DOT EDU
Keith A. Crabb         Keith AT UH DOT EDU
University of Houston  Operating Systems Specialist +1-713-743-1530