James, Thanks for that... it made me feel a lot better about my own situation
;-) Hopefully the end users will be able to bend some with regard to their
potential restore requirements. If you have been doing this for a while, make
sure your activity log is set to allow at least a month and then do a 'q actl
begindate=<<<a month ago>>> search=ANR1214I. This will tell you how much
backup/archive you have been pulling in on a daily basis. Then try to estimate
how much you are getting per tape and do the math and DO give yourself some room
for growth... best of luck. George





"<James> <healy>" <James.Healy2 AT AXACS DOT COM> on 02/15/2001 03:20:10 PM

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Subject:  Re: Formula to calculate # tapes required



George, Richard,
     Thanks for the responses. But I have 7 instances of TSM running, all
implemented last year. A consulting team calculated how much capacity we
would need and proposed it to management. Management cut that number in
half, hired me and handed it over.  I went to the well once already for
more tapes for our largest site, I figured doubleing the size of 200 3590K
tapes would be safe. Not a chance, we ate up the 200 new ones in 3 months.
Now 5 of the sites need more tapes and if I go to the well again I only
want to do it once.
By the way I've been using the k tapes (1400) in the last year and have had
<10 failures.




"George Lesho" <glesho AT AFCE DOT COM>@VM.MARIST.EDU> on 02/15/2001 03:55:57 PM

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Subject:  Re: Formula to calculate # tapes required


James... this is thorny issue considering the cost of these tapes. I use
Magstar
MP C-Format XL tapes and these guys
cost about $75 a pop. Be conservative when ordering and get more than you
think
you will need. I have experimented with
client compression vs drive compression and since I have a solid ETHERNET
infrastructure, chose to rely on drive
compression. Having said that, I snipped a portion of the result of a 'q
vol'
listing:

00E195                       ARTPOOL2        3575DEVC1            6,340.1
56.9       Full
00E1A6                       BKTPOOL2        3575DEVC1            6,809.4
84.6       Full
00E1AA                       ARTPOOL1        3575DEVC1            20,369.6
74.2       Full
00E1F2                       BKTPOOL1        3575DEVC1            9,238.7
50.5       Full
00E208                       BKTPOOL1        3575DEVC1            31,779.1
100.0       Full
00E20F                       ARTPOOL2        3575DEVC1            9,901.6
62.2       Full

Note that the estimated capacity of the 7 volumes varies wildly from a low
of
about 8 gigs to over 31 gigs... It all depends on
what type data you back up. Don't feel that any simple form would prove of
much
value unless it was able to compensate for
the effect of compression on different types of data or you could find a
site
where the data types were similar to yours, have
them multiply the estimated volume capacity for the separate volumes and
then
divide by the sum of the volumes to give you
a gestimate number on the amount you could expect per volume... Other
factors
are finding an average amount of data backed
up... once on a production basis with TSM, you could check the amount moved
during the backup of the primary tape storage
pool to the copy pool to get this number. Since I took this job over and
have
sorted out most of our requirements and schedules,
we have gone from about 30 gigs per day (during the week-only backups are
included in this number) to about 100 gigs per
day.  I guess what I am suggesting is to buy a supply of tapes, make the
people
with the money aware that you have not
established a baseline for the tape purchase and then work with the limited
supply of tapes for a few months to develop this
baseline and then purchase what you really require plus some percentage for
growth... Hope this helps... this is how I would
have done this, if I had known what I know now ;-)

George Lesho
Storage/System Admin
AFC Enterprises





"<James> <healy>" <James.Healy2 AT AXACS DOT COM> on 02/15/2001 02:34:02 PM

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Subject:  Formula to calculate # tapes required



Does  any one out there have a formula they use to calculate the number of
tapes they will use for an instance of TSM
I've tried to start with
          1) size of file systems to backup x 1 because you have at least 1
backup version of every file on the systems you'll back up(roughly)
          2) estimate the percentage of data that changes in you
environment daily, multiply that by the number of versions you'll keep
          add numbers 1 and two together to get a number that equals the
amount of data you'll have in your backup system onsite.
     here's where it gets fuzzy. Somehow you have to calculate the amount
of data you'll have co-located and non colocated. Find an average of the
capacity  your getting on your tapes. Then you'll have a number of what
your on-site capacity should be. Now you can double that if you're using
DRM and then somehow calculate in the factor of the re-use delay parameter
for the storage pools?????????????????