Raymond Raw wrote:
> We currently have 4 ICEBERG systems totaling 840 gigs. We're very
> happy with them. We were part of the early beta program and have
> been running ICEBERG's for 2 years. They perform pretty much as STK
> says although we've seen some inconsistencies with PAGE datasets on
> them.
>
> We've had ADSM databases on ICEBERG right from the start without any
> problems. However, there is one major point of consideration when
> putting ADSM databases on ICEBERG. (I suspect that RAMAC might have
> the same problem.)
>
> The ICEBERG size (200gig, 300gig etc.) is based on an assumption of 3
> to 1 data compression within the box. The real round and brown
> backing a 200gig ICEBERG is only about 75gig in size. (The 3 to 1
> ratio has actually changed with the newer boxes.) At any rate, the 3
> to 1 compression ration is generally very conservative and for most
> data we achieve better compression ratio. However, if you put
> precompressed ADSM data onto an ICEBERG, you don't achieve the 3 to 1
> ICEBERG compression and the box fills up faster than expected. The
> result being that a 200gig ICEBERG might only store 150gigs of
> compressed ADSM data.
>
> In the last few months STK has moved to newer faster compression
> chips that do a better job of ADSM precompressed data so this problem
> might be insignificant now. My suggestion would be to talk to STK
> specifically about ADSM data. They are certainly aware of what we
> experienced. Your STK rep can also run one of their field utilities
> against your 3390 databases and tell you exactly what compression
> rations you should achieve on the ICEBERG.
When you buy a 90-GB RAMAC string of DASD, you get 90 GB of DASD. This
problem does not apply. In fact, when we were looking at ICEBERG, the
problem you mention was indeed one of my reservations (not ADSM data per
se, but just in general). That is, if I'm paying for 200 GB, I expect 200
*usable* GB. I'd probably try to put that in a contract somewhere.
Andy Raibeck
Connecticut Mutual
203-987-3521
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