RE: Choosing data file size for a multi TB database?
- From: "Kevin Closson" <kevinc@xxxxxxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Fri, 2 Sep 2005 17:35:56 -0700
you'd have to look far and wide for a filesystem that still
imposes that lock on writes, WHEN direct IO is used...
VxFS,PolyServe, Sol UFS (forcedirectio mount)
and most other legacy unix derivations pulled that
lock for directio use cases long, long ago. Mid 90's.
Heck, I remember measuring the goodness of that
fix on Sequent Dynix with Oracle 6.0.27 back in
1990 :-)
________________________________
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Hameed, Amir
Sent: Friday, September 02, 2005 4:48 PM
To: oracle-l@xxxxxxxxxxxxx
Subject: RE: Choosing data file size for a multi TB database?
On very large data files running on buffered filesystem,
wouldn't the single-writer lock cause foreground processes (that are
trying to read data) to wait when the DBWR is check pointing?
________________________________
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Branimir Petrovic
Sent: Friday, September 02, 2005 6:54 PM
To: oracle-l@xxxxxxxxxxxxx
Subject: RE: Choosing data file size for a multi TB database?
What about checkpoint against tens of thousands of data
files, surely
more-merrier rule holds? For that reason (or due to a
fear factor) I
was under may be false impression that smaller number
(in hundreds)
of relatively larger data files (20 GB or so) might be
better choice.
Other very real problem with 10TB database I can easily
foresee, but
for which I do not know proper solution, is how would
one go about the
business of regular verification of taped backup sets?
Have another
humongous hardware just for that purpose? Fully trust
the rust? (i.e.
examine backup logs and never try restoring, or...) What
do people
do to ensure multi TB monster databases are surely and
truly safe
and restorable/rebuildable?
Branimir
-----Original Message-----
From: Tim Gorman [mailto:tim@xxxxxxxxx]
Sent: Friday, September 02, 2005 5:59 PM
To: oracle-l@xxxxxxxxxxxxx
Subject: Re: Choosing data file size for a multi
TB database?
Datafile sizing has the greatest regular impact
on backups and restores. Given a large multi-processor server with 16
tape drives available, which would do a full backup or full restore
fastest?
* a 10-Tbyte database comprised of two
5-Tbyte datafiles
* a 10-Tbyte database comprised of ten
1-Tbyte datafiles
* a 10-Tbyte database comprised of
two-hundred 50-Gbyte datafiles?
* a 10-Tbyte database comprised of
two-thousand 5-Gbyte datafiles?
Be sure to consider what type of backup media
are you using, how much concurrency will you be using, and the
throughput of each device?
There is nothing "unmanageable" about hundreds
or thousands of datafiles; don't know why that's cited as a concern.
Oracle8.0 and above has a limitation on 65,535 datafiles per tablespace,
but otherwise large numbers of files are not something to be concerned
about. Heck, the average distribution of a Java-based application is
comprised of 42 million directories and files and nobody ever worries
about it...
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