1. "DEFine DEVclass FORMAT=ULTRIUMC". "Ultrium" means without and 
"UltriumC" is with drive compression.

2. If your data is compressed at the client node TSM will be unable to 
compress further. Thus it write only about 100 GB (native capacity). And 
will report actual (compressed) ammount of data written to the tape.

3. Compression of data written to tape has nothing to do with reliability. 
It can affect only the performance.
For big client nodes (look recent example of Dwight Cook) client 
compression might be better. For many others drive compression might be 
better. There is no answer suitable for any case, the answer is "it 
depends"

Zlatko Krastev
IT Consultant






Murthy V Gongala <gmurthy AT IN.IBM DOT COM>
Sent by: "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>
25.11.2002 17:42
Please respond to "ADSM: Dist Stor Manager"

 
        To:     ADSM-L AT VM.MARIST DOT EDU
        cc: 
        Subject:        Re: tape become full in 21 percent.


Hi Daniel,

I have three questions about compression.

1. How do we define compression on a 3583 drive.
2. When you say you have tapes with 300-400GB data.....what type of
compresion are you using... Client Compression or Drive Compression.
3. How reliable are the tapes backed up with Drive Compression as compared
to Client compresion.

Thanks in advance.

regards
murthy




  
                      Daniel Sparrman   
                      <daniel.sparrman@        To: ADSM-L AT VM.MARIST DOT EDU  
  
 
                      EXIST.SE>                cc:    
                      Sent by: "ADSM:          Subject:  Re: tape become 
full in 21 percent. 
                      Dist Stor   
                      Manager"   
                      <[email protected]   
                      .EDU>   
  
  
                      11/25/2002 08:48   
                      PM   
                      Please respond to   
                      "ADSM: Dist Stor   
                      Manager"   
  
  



Full doesnt always have to be 100% utilized. The full is utilized+%
reclaim.

I have tapes being at 98% and being full...

So, that statement is not correct.

Of course compression has to do with pct util. If you have good
compression on your tapes, the pct utilization can reach numbers over est.
capacity(i have LTO tapes reaching 300-400GB per tape, with est. capacity
set at 200GB and native capacity at 100GB).

Normal operations include doing expiration. Expiration doesn't mean
removing all backup version Henke, only versions that has been expired due
to new versions added, or changed policys. So, I recommend doing exp inv
on a daily basis, if you haven't got any special issues such as
performance for not doing daily expiration.

Best Regards

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




Henk ten Have <hthta AT SARA DOT NL>
Sent by: "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>
2002-11-25 16:05
Please respond to "ADSM: Dist Stor Manager"


        To:     ADSM-L AT VM.MARIST DOT EDU
        cc:
        Subject:        Re: tape become full in 21 percent.


On 25-Nov-02 Zlatko Krastev wrote:
> Consider following scenario:
> 1. you backup say 40 GB
> 2. next day you backup 40 GB of which 35 GB updated - 35 GB from step 1
> expire.

  Only if you expire your backupdata after one day.

> 3. perform step 2 for four days.

  Who will expire his backupdata after one day?

  And compression has also nothing todo with Pct. Util., full is full and
  this number must be 100.0, and at least you must see an Estimated
Capacity of
  100/200Gb, or if client compression is on and the data is good
compressed,
  you normally will se the native size of the tape as Estimated Capacity.

  Cheers,
  Henk ten Have