Karel,

if you set the copygroup option on a primary storage pool, this will mean 
that every single session that sends data to the server will need to have 
it's own mount point. This will increase the need for tape drives in your 
copy storagepool. Whats cheapest? Buying extra disk for disk security, or 
new tape drives just so you can bypass the RAID-security on your disks? 
You could create a storage pool for your most important server(s), so that 
not all sessions have a storage pool with the copypool option set. 
However, most of my customers with 200-300 servers have alot of important 
servers..... Which means, for them, they would still need alot of drives 
to handle the copygroup option.

I would still go for disk security, either by using RAID internally in 
your disk subsystem, or by remote mirroring between disk subsystems(which 
is getting more common as companies begin to look at disaster recovery 
options). It's alot cheaper than trying to bypass disk security by using 
the copygroup option. If your disk subsystems are on a SAN, you could 
easily mirror(remote or locally) them in the operating system, which would 
make it possible to raise the level of uptime, as the TSM server wouldnt 
go down if you lost a disk subsystem or a RAID array.

Best Regards

Daniel Sparrman
----------------------------------
Daniel Sparrman
Exist i Stockholm AB
Propellervägen 6B
183 62 TÄBY
Växel: 08 - 754 98 00
Mobil: 070 - 399 27 51



"Bos, Karel" <Karel.Bos AT ATOSORIGIN DOT COM> 
Sent by: "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>
2004-07-22 09:17
Please respond to
"ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>


To
ADSM-L AT VM.MARIST DOT EDU
cc

Subject
Re: storage pool raid 1?






Hi,

Then again, if you configure these important server to directly write to a 
primary stg pool, with backupstg set to a copy pool, one backup will write 
to two destination at the same time. This will solve the raid 5 overhead 
and leave you with two copies of the "most" important data. 

Regards,

Karel 

-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU]On Behalf Of
asr AT UFL DOT EDU
Sent: woensdag 21 juli 2004 22:38
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: storage pool raid 1?


==> In article 
<OF3E4591C3.59EF37FE-ONC1256ED8.004B7645-C1256ED8.004BDA31 AT exist DOT se>, 
Daniel Sparrman <Daniel.Sparrman AT EXIST DOT SE> writes:


> I've seen occasions when disks have failed on a TSM server, and a user 
calls
> to have a single Word document retrieved. You want to be the one 
explaining
> to the user that the disk on the backupserver has failed, and that 
his/hers
> document cannot be restored? :=)


"Me too."


Additionally, there are increasing amounts of data stored on TSM which are 
not
even "just backups".

If you use the DB2 archive log transfer facilities, then between the time 
you
run the log upload and the next time you complete a stgpool backup, your 
DASD
has the only copy of that data in the universe.  With a RAID-5 in place 
and a
hot spare, I don't feel too much angst about this, but unmirrored would 
squick
me for sure.

We also use TSM as a data store for our content management application; 
That
DASD is in fact the primary data.  must must MUST be raided.


- Allen S. Rout