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VXFS mount options for Oracle DB on XP1024 disks array:

 
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Romaric Guilloud
Regular Advisor

VXFS mount options for Oracle DB on XP1024 disks array:

Hello,
I did read in a White Paper that for taking full advantage of a high-end disks array when ruuning a Oracle DB, it was advisable to mount data lvols with the following options:
"-o nodatainlog,mincache=direct,convosync=direct"

in order to skip LVM cache and benefit from large cache at disk array level instead.
Any comment/warning about this advice on the mount options?

Rgds,

Romaric.
"And remember: There are no stupid questions; there are only stupid people." (To Homer Simpson, in "The Simpsons".)
7 REPLIES 7
RAC_1
Honored Contributor

Re: VXFS mount options for Oracle DB on XP1024 disks array:

mincache=direct,convosync=direct requires OnlineJFS product.
There is no substitute to HARDWORK
RAC_1
Honored Contributor

Re: VXFS mount options for Oracle DB on XP1024 disks array:

datainlog/nodatainlog also required OnlineJFS. This applies only to small writes (less than 8kb), so if you are wrinting in sammll cunks, then only enable disable this option.
There is no substitute to HARDWORK
Jean-Luc Oudart
Honored Contributor

Re: VXFS mount options for Oracle DB on XP1024 disks array:

Hi

"in order to skip LVM cache and benefit from large cache at disk array level instead" :
I suppose yuo meant the vxfs cache (not LVM). The file systems cache and XP array cache are 2 different things. The XP cache is part of the backend storage and that you use or not file systems cache does not affect it.

The options you mention for Oracle will be good if the access type is mostly random. If not you may find the file systems cache may helpin some instances.
The purpose of these options (require OnlineJFS product) is to bypass the file system cache and therefore you could dedicate more memory on the system to the Oracle SGA as opposed to the file systems.

see attachment
Unix Performance Cookbook.

Regards
Jean-Luc
fiat lux
Eric Antunes
Honored Contributor
Solution

Re: VXFS mount options for Oracle DB on XP1024 disks array:

Hi Romaric,

It's a good advice!

But be sure you have a well tuned database. Check, for example, if you have a good Buffer Cache Hit Ratio:

select round(((1-(sum(decode(name, 'physical reads', value,0)) /
(sum(decode(name,'db block gets', value,0))+
(sum(decode(name, 'consistent gets', value, 0))))))*100),2)
|| '%' "Buffer Cache Hit Ratio > 95%"
from v$sysstat;

Best Regards,

Eric Antunes


Each and every day is a good day to learn.
Jean-Luc Oudart
Honored Contributor

Re: VXFS mount options for Oracle DB on XP1024 disks array:

To check the performance at Oracle level, install perfstat and monitor the Oracle performance.
You will have an history (and baseline) for performance
http://www.oracle.com/technology/deploy/performance/pdf/statspack.pdf

Regards
Jean-Luc
fiat lux
Zinky
Honored Contributor

Re: VXFS mount options for Oracle DB on XP1024 disks array:

This VxFS (aka OnlineJFS) mount option has been the "recipe" for "cooked" filesystems for years. It is intended to enable what is called DirectIO so Filesystem Buffers are limited and so you get as close a performance to "raw" storage.

Still, the BEST Oracle storage on *any* disk infrasrtcuture (whether "cache-centric" --- XP for instance or not) is to store your Database raw - period.

Tools within LVM or VxVM allow for easy management of Raw storage -- contrary to earlier myths and 'lore that using raw storage is difficult.
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Romaric Guilloud
Regular Advisor

Re: VXFS mount options for Oracle DB on XP1024 disks array:

Thanks all.
"And remember: There are no stupid questions; there are only stupid people." (To Homer Simpson, in "The Simpsons".)