Tim Hare wrote:
[...]
We're trying to evaluate switching to Tape Mount Management versus virtual
tape. This post is not about the pros or cons of doing it; rather we're
trying to analyze what some of the costs are.
[...]
That's the point. IMHO you *cannot* skip the pros&cons analysis. It's
quite obvious, that virtual tape system (I'm talking about IBM or STK
solutions now) costs more than real tape solutions since the same amount
of drives, robots and medias could hold the same amount of data written
natively. At least in theory. In practice, the main feature you get with
virtual tape is convenience and flexibility. How much worth is it ?
Well, id depends on your environment (the more systems, the more
important), you budget constraints, your system setup, your operations
skills.
There is no strict formula or some treshold. I think the only advice you
can get is to ask proper questions, like the following:
- how many systems/sysplexes do you have
- how is organized your Tape Mgmt System (one common vs several
separated db's).
- are you able to get rid of jobs writing small amounts of data directly
to tape - I mean HSM and/or TMM.
- what are your DR requirements and DR facilities (i.e. your own DR
centre connected through DWDM links)
- is your operations staff smart enough to easily manage manual vary
on/off the drives across LPARs according to scheduled backup sessions or
current needs. Caution: IBM ATAM or CA-MIA could do the work.
- what's your amount of data to be kept on the tapes and what amount of
data is being written to tape everyday.
- what is tape activity during the day (recalls, reads)
- what are your demands on performance (note native drives are usually
faster than virtual drives).
HTH
--
Radoslaw Skorupka
Lodz, Poland
--
BRE Bank SA
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Wedug stanu na dzie 01.01.2007 r. kapita zakadowy BRE Banku SA (w caoci
opacony) wynosi 118.064.140 z. W zwizku z realizacj warunkowego
podwyszenia kapitau zakadowego, na podstawie uchwa XVI WZ z dnia 21.05.2003
r., kapita zakadowy BRE Banku SA moe ulec podwyszeniu do kwoty 118.760.528
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