topic Re: filesystem block size in Operating System - HP-UX

filesystem block size

pa8700 — Tue, 02 Feb 2010 15:58:55 GMT

wether I can change the block size of a file system once created. Wether it needs down time ? some body sugested that 8k is good for oracle performance

Re: filesystem block size

Steven E. Protter — Tue, 02 Feb 2010 16:07:33 GMT

Shalom,

To change this you would need to back up your data, rebuild the logical volumes and file systems and then restore the data.

Don't bother, a number of people have actually tested this concept out and not gotten a significant boost in oracle performance.

Proper tuning of kernel parameters, system patching and management of the Oracle SGA settings all have far more impact on performance than block size on the file system.

SEP

Re: filesystem block size

James R. Ferguson — Tue, 02 Feb 2010 16:10:16 GMT

Hi:

The block size ('bsize') is set at creation time and can't be changed thereafter.

The block size for files on the file system represents the smallest amount of disk space allocated to a file. The values are powers of 2 and range from 1024-8192 bytes with an appropriate default being chosen based on the size of the filesystem at creation. See the 'mkfs_vxfs' manpages for more information.

Regards!

...JRF...

Re: filesystem block size

Bill Hassell — Tue, 02 Feb 2010 21:00:32 GMT

> some body sugested that 8k is good for oracle performance

Years ago (probably more than 15), Oracle recommended this for 'performance' in a blanket statement for all flavors of Unix. Unfortunately, this statement still persists even though it has no relevance with current VxFS filesystems (and very little effect for HFS).

The biggest change in performance for Oracle is to look at the DB design and the queries. Reducing disk I/O in Oracle is many times more effective than fiddling with filesystems, striping, cache sizes, etc.

Re: filesystem block size

Suraj K Sankari — Tue, 02 Feb 2010 21:06:40 GMT

Hi,

>>wether I can change the block size of a file system once created.
As said above you need to take backup and rebuild the same.....

Wether it needs down time ?
down time for what server?
if its about server then no. for file system then you need to distroy the vg and recreate it again...

Suraj

Re: filesystem block size

Johnson Punniyalingam — Wed, 03 Feb 2010 02:25:39 GMT

>>wether I can change the block size of a file system once created<<<

you need use "newfs" command to specfiy your bloack size once you have create file system using lvcreate" than follow has below

newfs -F vxfs -b 8192 -o largefiles /dev//r

>>>>Wether it needs down time ?<<<

if its new file system creation - NO downtime required

Re: filesystem block size

Johnson Punniyalingam — Wed, 03 Feb 2010 02:27:05 GMT

>>some body sugested that 8k is good for oracle performance<<

As per the attachment , Yes