[ADSM-L] Who/What determines tape compression
TSM servers - AIX v220.127.116.11 AIX 5.1 (yes I
know...unsupported....working to phase out and replace with Linux
I am currently dealing with a strange issue relating to data compression
levels (or the lack there-of) I am hoping someone can explain or point-out
where to look.
We originally had 4-3592E05 drives in our 3494 tape library. We just added
3-more. FWIW, these drives have the new "encryption" feature (we didn't
ask for it.....were told we had to take it.....cost us $3,000 more).
Ever since we added the new drives, I am noticing a drop in the
compression I am achieving from these drives on the AIX TSM server that
owns the library.
Before these new drives were installed, I achieved 1.8TB on one cartridge
owned by this server. I didn't do much 3592 usage since I simply didn't
have the drives to share amongst 4-servers.
Since these new drives have been put into use and I have agressively
started migrating data from 3590K tapes, I am only seeing <600GB per
cartridge. This is almost no compression at all.
I did a complete removal and re-add of all AIX tape and TSM devices and
bounced the TSM server. It is obviously seeing and using them, with no
issues. All drives have the latest firmware, D3I1_A38.
Nothing has changed with the DEVCLASS. All 3592's are using the same
devclass. It is configured as 3592-2C. Scaled at 100%.
No, I can't say that the lower compression is coming from the new drives,
Any thoughts on what gives ? Why the change in compression ratio (this is
a high-mix of various kinds of data. I should be getting at least 1TB vs
my Notes systems which can't compress much and I get around 700-800GB per
Virginia Commonwealth University
Office of Technology Services
University Computing Center
e-mail: zforray AT vcu DOT edu