Re: [Veritas-bu] No of LTO Tapes used for backups
2008-09-26 11:35:14
This is a non-trivial exercise. If you are not driving your LTO-2 drives at full speed, you certainly won't drive the LTO-4 drives at full speed and you'll run out of drives. Even if you are driving them at full speed today, you need to prove to yourself that you have enough headroom in your entire infrastructure to be able to drive the LTO-4s at full speed. That's network, storage, servers, and clients.
Any time you upgrade to faster drives, you need to seriously consider if the drives were the bottleneck. If not, you could potentially slow things down rather than speed them up since the new drives may shoe-shine whereas the older drives might not have.
LTO-4 drives have more capacity, obviously, than the LTO-2 drives. However, you need to factor in how full the tapes are going to be when you vault (assuming you vault). If you are currently ejecting a half-full LTO-2 tape, you're likely to eject the LTO-4 tape when it's nowhere near full, and then you could potentially need the same number of LTO-4 tapes as LTO-2 tapes.
Unless you have a very, very clear understanding of your environment and all of the bottlenecks, and how they'll change when you put in faster but fewer tape drives, you're not going to be able to put together a good sizing estimate. Sometimes you just have to guess and hope for the best, and have a plan to expand quickly if what you thought was going to happen didn't happen.
.../Ed On Fri, Sep 26, 2008 at 9:07 AM, WEAVER, Simon (external) <simon.weaver AT astrium.eads DOT net> wrote:
Thank you. Not sure if this is the right tool, but I am
looking at the best way to size up a new library.
I use LTO2 x 12 drives and going for a SUN SL500 with a
proposed 8 drives.
Environment runs 24 x 7. currently Library has 636 slots
all in use. Of these, 60 - 70 can be used from scratch in a
weekend.
Is there a good way to work out how many slots I could well
need when going from 12 x LTO2 drives to a SL500 8 x LTO4
drives
Thanks in advance
Simon
bpimagelist has a -media option that kicks out the tape
used, so you should be able to throw something together using the output of
"bpimagelist -hoursago 24 -media -l" (or -U if you want it pretty, etc).
User
friendly output looks like :
Media ID
Last Written Server --------
---------------- ---------- ABCJ3O
09/25/2008 03:31 backupserver1 ABCJ4E
09/25/2008 04:23 backupserver2 ABCJ3I
09/25/2008 04:03 backupserver5 ABCJ3B
09/25/2008 03:42 backupserver4 ABCJ1J
09/24/2008 21:52 backupserver3 ABCJ2A
09/24/2008 21:52 backupserver2 ABCJ5C
09/25/2008 08:35 backupserver1
- John Nardello
Hi all I need to know if there is a simple command I can run that
will tell me how many Media tapes have been used overnight for a period of 24 or
72 hours.
Just trying to size up a new library,
and want to be sure I correctly size the slots for future
backups.
Regards
Simon
.../Ed
Ed Wilts, RHCE, BCFP, BCSD, SCSP, SCSE
ewilts AT ewilts DOT org
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