If you have Data Domain and want to get more granular information on compression, in addition to running “ost lsu show compression “ or “filesys show compression”
from the Data Domain itself, you can also run “filesys show compression” with additional arguments “[filename] [last n {hours | days}]”, where a wildcard such as * can be used within the filename.
“filesys show compression /backup/ost/<LSU_NAME>/*” produces a report that contains a line for every image fragment that looks like the following, where “bytes”
is actual size of backup, “g_comp” is size on Data Domain after global compression (dedupe), “l_comp” is size on Data Domain after local compression (i.e. LZ compression after dedupe) and “bytes/storage_used” is the compression ratio, followed by a summary
with totals.
/backup/ost/<LSU_NAME>/<BACKUP_IMAGE>_<COPY>_<FRAGMENT>:1300250930:<POLICY>:4:1::: mtime: 1300264487182774391, bytes: 4,577,820,672, g_comp: 380,239,733, l_comp:
109,514,404, meta-data: 1,164,084, bytes/storage_used: 41.4
Update the SSH Authorized Keys file on the Data Domain (using “adminaccess add ssh-keys” per Data Domain command reference guide) so you aren’t constantly prompted
for a password, and a script like the following ran from a Media Server would produce a space delimited file with client, compression and size on Data Domain (after dedupe and compression) that can be easily opened and manipulated in Excel.
for client in `ssh sysadmin@<DATADOMAIN> "filesys show compression /backup/ost/<LSU_NAME>/*"|awk -F\/ '{print $5}'|awk -F_ '{print $1}'|sort -u`; do ssh sysadmin@<DATADOMAIN>
"filesys show compression /backup/ost/<LSU_NAME>/$client*"|awk '{if ($1 == "Total") printf client" "$5; else if ($1 == "Locally") print " "$4}' client=$client >>/var/tmp/<DATADOMAIN>.`date +%m%d%y`.log; done
From: veritas-bu-bounces AT mailman.eng.auburn DOT edu [mailto:veritas-bu-bounces AT mailman.eng.auburn DOT edu]
On Behalf Of Rusty.Major AT sungard DOT com
Sent: Friday, April 22, 2011 4:21 PM
To: VERITAS-BU AT MAILMAN.ENG.AUBURN DOT EDU
Cc: VERITAS-BU AT MAILMAN.ENG.AUBURN DOT EDU; veritas-bu-bounces AT mailman.eng.auburn DOT edu
Subject: Re: [Veritas-bu] EMC Data Domain OST Vs VTL with NetBackup
You will get little to no dedupe if your DBA or DB agent performs any compression or encryption on the db backup before it gets onto the DD. Always
note, what you will get and what someone else will get will always differ somehow, so take the below with a grain of salt.
I have been seeing between 18 and 20 times compression for an environment that is made up of about 50 VMs and has several DB servers. I can't give you numbers more granular than that because we
are using only one LSU.
Rusty Major, MCSE, BCFP, VCS ▪ Sr. Storage Engineer ▪ SunGard Availability Services ▪ 757 N. Eldridge Suite
200, Houston TX 77079 ▪ 281-584-4693
Keeping People and Information Connected® ▪
http://availability.sungard.com/
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Thanks rhugga
I also have a quick question to all experts on dedup ratio that you see on database backup, for e.g. SQL, DB2 & Oracle.
What is the usual ratio you see with database backups using native application backup utilites or using NetBackup Agents? Does it make any difference do it?
Suppose if DBA's generates 1TB of SQL native database backup flat files for a given server and if I back up flat files using NetBakcup n keep it for 5 weeks essentially backing up 30TB of data then how much compression one would see and what factors does
it depend on.?
Thanks.
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