Hi Murthy
1. Either using ULTRIUMC, or DRIVES as device format type. This is
settable through upd devclas XXXX format=ULTRIUMC/DRIVES. Notice that this
will not apply to all your volumes, only to libray volumes with scratch
state(which means next time the tape is used, it will be using
compression).
2. When reaching 300-400GB of data on one tape, we use drive compression.
This is not applicable to all kinds of data(normally databases, text files
and so on). Files that has already been compressed, such as JPEG and GIF
files, will have a lower rate of compression.
3. With reliability, I asume you mean on a security based level? The
reliability wont change if you use either compressed or non-compressed
media. The security is more based on the KIND of media you use, such as
DLT, LTO, 9840, 3590 and so on. If you mean compression level, I have the
experience that hardware compression is more "reliable" compared to client
compression. However, there might be people having other kind of
experience.
Hope this answers your questions
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
Murthy V Gongala <gmurthy AT IN.IBM DOT COM>
Sent by: "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>
2002-11-25 16:42
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
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