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If you use RMAN for your Oracle backups, it is already
stripping off the unused blocks above the HWM, so your compression shoud only be
relative to the compressibility of the used/previously used blocks. If you are
using other tools than RMAN to back up the files, then yes you can get fantastic
rates of compresion as the blocks above the HWM are zero filled
blocks.
depends...
DBs
tend to be padded with a ton of dead space.
Any
tape drive, VTL, or de-duping Disk target will compress most databases quite
well.
The
problem is, you're still pulling that data off the host.
If the
client has the CPU cycles available, it can compress the data itself and
minimize the data you're sending over the network, or in the case of SAN media
servers, over the FC infrastructure.
if
there's any dead space in the file when it hits the target, you'll still get
some compression there as well.
Paul
--
We get unbelievable compression on our EMC CDL on tapes
that are used for DB backups. I would recommend turning on compression
only at the CDL/EDL level.
An
example:
(A 100 GB max virtual
tape, with compression enabled on the CDL)
From NetBackup Media:
Media ID
images
kilobytes
AXB009
HCART 00_003_TLD
AIX 30
<snip> <snip>
5
2150450784 0 Full
0
From CDL Report:
Name,VID,Barcode,Current:Allocation:(MB),Location,Maximum:Capacity:(MB),Used:Size:(MB),Data:Written:(MB),Compression:Ratio,
VirtualTape-01075,1075,AXB009,100352,In Slot:
11,100352,100177,2100050,20:1,
That is 20:1, and I've actually seen it higher on different
backups.
Jared M.
Seaton
Recovery Administrator
Mylan Inc.
304-554-5926
304-685-1389
(Cell)
"mark wragge"
<mark_t_wragge AT yahoo DOT ie>
Sent by: veritas-bu-bounces AT mailman.eng.auburn DOT edu
03/12/2008 06:34 AM
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Subject
| [Veritas-bu] oracle policy with
compression turned on |
|
How does the compression option on an Oracle policy function? Is it the
same as turning on compression on a standard filesystem backup OR is this a
compression feature specific to oracle database backups?
I am considering turning on compression
on a Virtual Tape Librayr and on the oracle policy. Should i just turn it on
on the VTL (EMC EDL).
Thanks.
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