My personal recommendation is to evaluate upgrade to 3590H. I am surprised
why this is not the IBM's first proposal. Arguments:
LTO definitely is downgrade to what you have now both in terms of
performance and reliability as others already answered. Higher capacity
per volume and much lower price are main advantages. Former will soon
change while the latter will never change.
For large data streams native rate of LTO (15MB/s) is higher than for 3590B (9MB/s)
and slightly above 3590E/3590H (14MB/s). Utilizing different
compression algorithm on compressed data the rate of 3590B (27MB/s) is
comparable to LTO (30MB/s) while 3590E/H definitely outperforms it (42MB/s). But for
smaller files you have to count also mount time and there 3590s are more than two
times faster than LTO. With LTO is much
harder to get some benefit from filespace collocation while this can help
in many cases with high-end tape drives.
Reliability of LTO is not bad but cannot compare to 3590/9x40.
Bigger volume ought not be such a problem for reclamation - it should be
nearly the same would you reclaim 3 volumes 100 GB each or 30 volumes 10
GB each for same average percentage.
If LTO gets damaged you for sure will have to restore much more. But this
is true whenever you go to *any* higher capacity technology - just the
same for 3590E/H or 9940.
Same remark for collocation - it is not related to technology but only to
capacity of the cartridges. There are two ways to prevent it - stay with
(older) lower capacity technology or limit maxscratch forcing more than
one node's data to be put on a volume. And you can always define several
pools with different maxscratch settings so it ought not be a big problem.
Upgrade to 3590H would be more expensive than brand new LTO but you will
get much better product. All remarks about performance and reliability
ought to be enough to justify higher price. You will not be forced to get
rid of those 5500 cartridges and buy new LTO ones. You will get 60 GB per
tape as from 9940A. SAN-attachment also is not a problem with fiber drives
and dual-ports (vs. single ported LTO) add to reliability.
StorageTek silos with 9840/9940 drives are very good products. If we want
to compare apples with apples we have to compare them with IBM 3494 + 3590B/E/H
drives. Comparison with DLT or LTO would be apples vs. oranges. So the statement "it
costs twice" returns nothing useful. Count again the
need for new 9x40 cartridges and plan what will do with old 3590 ones.
But for me this would be replacement of Mercedes with Cadillac - both are
very good, both are very expensive and both give the same results with
different vendor's approach.
Zlatko Krastev
IT Consultant
Please respond to "ADSM: Dist Stor Manager" <[EMAIL PROTECTED]>
Sent by: "ADSM: Dist Stor Manager" <[EMAIL PROTECTED]>
To: [EMAIL PROTECTED]
cc:
Subject: IBM vs. Storage Tek
Hello,
I know I've asked about this before, but now I have more information so I
hope someone out there has done this. Here is my environment for TSM.
Right now it is on the mainframe and we are using 3590 Magstars. We have
a
production and a test TSM server and each has about 13 drives and a total
of 5,500 tapes used for onsite and offsite tape pools between the 2
systems. Two scenarios are being considered (either way TSM is being
moved
onto our SAN environment with approximately 20 SAN backup clients and 250
LAN backup clients and will be on SUN servers instead of the mainframe)
Here is what I estimated I would need for tapes:
3590 9840 9940A LTO
10 GB 20 GB 60 GB 100 GB
Production
Onsite 1375 689 231 140
Offsite 1600 800 268 161
Total 2975 1489 499 301
Test
Onsite 963 483 163 101
Offsite 1324 664 223 135
Total 2287 1147 386 236
Grand
Total 5262 2636 885 537
1. IBM's solution is to give us a 3584 library with 3 frames and use LTO
tape drives. This only holds 880 tapes and from my calculations I will
need about 600 tapes plus enough tapes for a scratch pool. My concern is
that LTO cannot handle what our environment needs. LTO holds 100 GB
(native), but when a tape is damaged or needs to be reclaimed the time it
takes to do either process would take quite some time in my estimation.
Also, I was told that LTO is good for full volume backups and restores,
but
that it has a decrease in performance when doing file restores, archives
and starting and stopping of sessions, which is a majority of what our
company does with TSM. Has anyone gone from a 3590 tape to LTO? Isn't
this going backwards in performance and reliability? Also, with
collocation, isn't a lot of tape space wasted because you can only put one
server per volume?
2. STK 9840B midpoint load(20 GB) or 9940A(60 GB) in our Powderhorn silo
that would be directly attached to the SAN. From what I gather, these
tapes are very robust like the 3590's, but the cost for this solution is
double IBM's LTO. We would also need Gresham licenses for all of the SAN
backed up clients(20).
Does anyone know of any sites/contacts that could tell me the
advantages/disadvantages of either solution? Any opinions would be
greatly
appreciated.
Thanks!!!!
Joni Moyer
Associate Systems Programmer
[EMAIL PROTECTED]
(717)975-8338
