The typical reason for this is that people are compressing at the client
level and not realizing it.
Check some of your larger "compressible" clients to see if the compression
option is on.
If so, it's compressing before it gets to the tape drive and you don't see
the ratio there.
If you have no network limitations, turn off compression at the client.
(It can be forced off from the server with "upd n NODE comp=no" or "upd n
* comp=no" for all nodes
Tape hardware compression is faster and probably better
Regards,
Shawn
________________________________________________
Shawn Drew
Internet
JCL AT GWSC.VIC.EDU DOT AU
Sent by: ADSM-L AT VM.MARIST DOT EDU
10/26/2009 11:56 PM
Please respond to
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Subject
[ADSM-L] Poor compression results
Hi everyone,
Please bear with me, I'm a small time school network admin :-)
In short, the compression ratios I'm seeing appear to be quite poor. I'm
looking for guidance on determining if 'thats all I'm going to get' due
to hardware restrictions or if there is hope.
The setup:
We have a single instance of TSM (was 5.4, now 6.1) running on a single
Win2k3 server, an IBM 3550 with 6GB ram. This is directly connected, no
FC switch (thats coming) to a EMC CX300 SAN via 2GB FC. We run a IBM
TS3200 4ru tape library with 2x 3580-TD3 drives (LTO3) connected on a
single Ultra-320 SCSI card - Adaptec 29320ALP.
Currently we pull from the clients (about 15 total) and spool it to the
EMC SAN via a diskpool (500GB), the majority of clients are running
1gbit. Once that hits 50% utilisation, its migrated to tape. Each night
we backup both the disk and tape pools to an offsite tape pool.
All of this is done outside of business hours during exceptionally low
utilisation times.
Below is a sample of the various volumes we have.
H:\TSMDATA\SERVER1\POOL S\DISK0.DSM DISK DISK 51.2 G
023335L3 TAPE LTO3 420.7 G
023336L3 TAPE LTO3 417.4 G
023337L3 TAPE LTO3 438.0 G
OFF001L3 OFFSITETAPE LTO3 445.7 G
OFF002L3 OFFSITETAPE LTO3 439.9 G
OFF003L3 OFFSITETAPE LTO3 488.4 G
I believe I have the config in TSM setup right..
tsm: SERVER1>q devcl
Device Device Storage Device Format
Est/Max Mount
Class Access Pool Type
Capacity Limit
Name Strategy Count
(MB)
--------- ---------- ------- --------- ------
-------- ------
DISK Random 1
FILEDEV1 Sequential 1 FILE DRIVE
102,400.0 32
LTO1 Sequential 0 LTO ULTRIUMC
1
LTO3 Sequential 2 LTO DRIVE
409,600.0 2
tsm: SERVER1>q drive f=d
Library Name: LIBRARY
Drive Name: MT4.0.0.2
Device Type: LTO
On-Line: Yes
Read Formats:
ULTRIUM3C,ULTRIUM3,ULTRIUM2C,ULTRIUM2,ULTRIUMC,ULTRIUM
Write Formats:
ULTRIUM3C,ULTRIUM3,ULTRIUM2C,ULTRIUM2
Element: 256
Drive State: LOADED
Volume Name: 092394L3
Allocated to:
WWN:
Serial Number: 1210170739
Last Update by (administrator): ADMIN
Last Update Date/Time: 05/05/2009 09:30:24
Cleaning Frequency (Gigabytes/ASNEEDED/NONE): NONE
Library Name: LIBRARY
Drive Name: MT5.0.0.2
Device Type: LTO
On-Line: Yes
Read Formats:
ULTRIUM3C,ULTRIUM3,ULTRIUM2C,ULTRIUM2,ULTRIUMC,ULTRIUM
Write Formats:
ULTRIUM3C,ULTRIUM3,ULTRIUM2C,ULTRIUM2
Element: 257
Drive State: LOADED
Volume Name: OFF029L3
Allocated to:
WWN:
Serial Number: 1210306202
Last Update by (administrator): ADMIN
Last Update Date/Time: 05/05/2009 09:30:30
Cleaning Frequency (Gigabytes/ASNEEDED/NONE): NONE
Given that a LARGE amount of our backups are SQL databases and
transaction logs, I was expecting better than 1.075 to 1 compression
ratio.
My understanding that LTO3 likes to run at or about 80MB/s. Ultra320
will run up to 320MB/s. The slowest portion of our setup is the 2Gb/s FC
connection into the SAN.
Your thoughts would be greatly appreciated.
Maybe I need to force the devclass to use compression rather than give
it the option.. but I would assume compression is favoured over not?
Regards,
Jason Clarke
------------------
Network Manager
Glen Waverley S.C.
p 03 8805 6750
m 0418 145 318
e jcl AT gwsc.vic.edu DOT au
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