Re: [Networker] How to tell how much physical tape is being used?
2007-04-24 16:58:06
Stan Horwitz wrote:
On Apr 24, 2007, at 4:04 PM, George Sinclair wrote:
Excellent point, but if that 10 GB is being compressed down to say 5
GB via the 'compressed' option, for example, then you're only using 5
GB of tape, but if your rman script isn't using the 'compressed'
option, and you're sending all 10 GB to the drive then the drive is
still gonna use hardware compression, so how do I determine which
method actually used less tape? Maybe it's a toss up?
If you are using hardware compression, then using software compression
on top of it (for any kind of data, Oracle or other) will give rise to
the possibility that the data might actually take up more space on
your tapes, not less. Usually, hardware compression is the way to go
and software compression should be used only in a narrow set of
circumstances such as a situation where a client has a lot of
compressible data and a slow network pipe.
Good point, and I agree. It's just that Oracle's compression was so
massive that I got to thinking that even if the subsequent hardware
compression actually increased that size, the reported backup sizes were
on an order of magnitude smaller than when no Oracle compression was
used. This got me thinking that the data must be highly compressible
even though Oracle's compression was being used. As a result, perhaps
not using Oracle's compression and just letting hardware compression
handle it might still result in the same level of compression even
though the reported backup sizes would be larger.
I think we'll turn off Oracle's compression and just use the built-in
hardware compression. I was just curious if there was a way to determine
which method actually used more physical tape.
George
To sign off this list, send email to listserv AT listserv.temple DOT edu and
type "signoff networker" in the body of the email. Please write to
networker-request AT listserv.temple DOT edu if you have any problems with
this list. You can access the archives at
http://listserv.temple.edu/archives/networker.html or
via RSS at http://listserv.temple.edu/cgi-bin/wa?RSS&L=NETWORKER
--
George Sinclair - NOAA/NESDIS/National Oceanographic Data Center
SSMC3 4th Floor Rm 4145 | Voice: (301) 713-3284 x210
1315 East West Highway | Fax: (301) 713-3301
Silver Spring, MD 20910-3282 | Web Site: http://www.nodc.noaa.gov/
- Any opinions expressed in this message are NOT those of the US Govt. -
To sign off this list, send email to listserv AT listserv.temple DOT edu and type
"signoff networker" in the body of the email. Please write to networker-request
AT listserv.temple DOT edu if you have any problems with this list. You can access the
archives at http://listserv.temple.edu/archives/networker.html or
via RSS at http://listserv.temple.edu/cgi-bin/wa?RSS&L=NETWORKER
|
|
|