I hope you will excuse me to be so direct but I think that you last answer
is stupid, did you ever look at the price of a single drive library
compared to a three drive library ? And I don't talk of the fact that most
3 drives libraries require the advanced library TSM feature which
multiplies the price of TSM by 4 ! But I think this is why you talk of a
BIG favour, it is because the price is BIG. If you compare the whole
solution, you will see that the whole solution has a price multiplied bye 4
or more which makes it unaffordable for most companies.
I completely agree with you that a three drive (or at least two drives)
library is far more practical with TSM but it is very expensive. In
addition, what is the use of buying a 2 or 3 Tbytes library when you need
only 200 or 300 Gbytes.
I saw in this list some people saying that TSM is only for big companies
and that if you can't afford a 2 drives library, you should'nt buy TSM. I
also disagree with that, TSM has some functionalities which make it usefull
also for small companies (I had another storage software before and for
example, I saw that with TSM, I could reduce the number of tapes to buy,
and then to manage by 2 or 3)
I think it wouldn't be a lot of work for Tivoli just to add a few
functionnalities which would allow small companies to use it with a single
drive or with a small library. Don't forget that many companies uses only a
single drive on each server and if you talk to them of the price of TSM
with advanced library and a 3 drives library, they laugh.
Anyway, the cheapest configuration which I use without buying a "BIG"
library and which is practical with TSM is to add an external drive which I
use for the copy pool. You just need to have a drive which can contain at
least the amount of data you backup each day.
It is not a real problem that you have to change the copypool tapes each
day as it is what everybody make usually, even with a library. The only
thing which is a bit annoying is that I still didn't find a best way than
creating a script which set all the copypool tapes to writeonly except the
tape which is intended to be used. And I have to modify the script each
time I change a tape which is full. But I must admit I still didn't
understand very well how TSM manages the use of a single external drive.
Sometimes, I can put any tape and everything is ok, and some other times, I
put in an empty tape and TSM asks me for another. This is why I had to
create this script.
But I still didn't spend the time I should have to solve this problem.

Etienne GUILLAUMONT
e-mail : etienne AT rgb-technologie DOT fr

RGB Technologie
Parc d'Innovation, Batiment PYTHAGORE
11 Rue Jean SAPIDUS
67400 ILLKIRCH
Tél :  03 90 40 60 60
Fax : 03 90 40 60 61


                                                                                
                                   
                    Mark                                                        
                                   
                    Stapleton            To:     ADSM-L AT VM.MARIST DOT EDU    
                                          
                    <stapleto@BER        cc:                                    
                                   
                    BEE.COM>             Subject:     Re: Off site copy with 
one drive???                          
                    Sent by:                                                    
                                   
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                    01/10/02                                                    
                                   
                    13:19                                                       
                                   
                    Please                                                      
                                   
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                    "ADSM: Dist                                                 
                                   
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From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU]On Behalf Of
Etienne Brodeur
> Is it possible if I have a one drive library to use a copy storage pool
> for my backups?

Yes.

> I can backup to disk, then backup the diskpool to the copypool.  (this
way
> I should have all my data onsite and offsite).

Exactly. You backup from diskpool to offsite pool, and then you migrate
from
diskpool to primary tape pool.

> How do I then reclaim my copypool volumes?

You can't. TSM doesn't support a disk-based reclamation pool for
reclamation
of offsite tape pools.

> I can't reclaim to disk like I
> do with my onsite volumes for some reason (I don't see why not since the
> DB can track which file is on which onsite tape mount it and copy it to
my
> reclaimpool on disk.  Once that is done it can mount a scratch or
copypool
> volume and the offsite volumes would be reclaimed no?

One-drive libraries are pretty much worthless. Particularly if you have
large-capacity tape volumes, your disk-based reclamation pool needs to be
at
least 40% of the maximum size of the tape volume. In the case of LTO tapes,
that means 80GB of disk space for the reclamation pool.

Do yourself a BIG favor. Get a three-drive library.

--
Mark Stapleton (stapleton AT berbee DOT com)
Certified TSM consultant
Certified AIX system engineer
MCSE