OS Block size

Many different ways, depending on your OS and file system manager. HP uses a tweaked version of Veritas. You can access your JFS logical volumes through SAM and there you can see your block size. This is actually adjustable when you create a new volume.

The defaults are 512, 1024, 8192 (bytes) by most vendors. 8192 is very rare.

SCO manages by OS and not file system. The SCO command for the whole OS is cmchk.

If neither of these help I still might have an answer depending on your OS and volume manager so please list.

Hi,

Thanks for your reply that has really helped. I actually wanted to know the commands to get the OS Block size of the following UNIX systems:

1. Solaris
2. SCO - ('cmchk' - you have already answered.)
3. HP-UX
4. Linux

Your reply would be really helpfull.

K CHATTERJEE

I don't know the commannd to verify, but I know the default for Solaris and Linux is 8192. For HP, the default is 4096. This is also what will come up when you allocate a new file system through SAM (by default) but is adjustable per file system.
Solaris can also be changed with the -b option of newfs when creating a new filesystem. I'm sure Linux can be changed per file system as well, but I don't know how.

I guess you just wanted to know how the OS applications treat data so the filesystem stuff may not be important this time, but you never know.

I hope this helps a little more.

Hi,

Actually I wanted to know the OS Block size of the already created volumes in those OSs as while configuring 'init.ora' file in oracle I can determine which multiplication of OS Block size should I use to define Oracle Block size.

If the OS blck size of already created volumes are visible through SAM, my question is answered.

Thanks.

K CHATTERJEE

Solaris: newfs -Nv /dev/rdsk/cxtxdxsx

In a Tru64 UNIX system, the default block size is 8192 bytes. The Oracle block size should also be set to 8192 bytes.

This information is maintained in the superblock for that file system, so anything that queries that can provide usefull clues to the blocksize. On solaris systems, a df -g will yield this. Do a man page on the other unix systems on df to find theoption that gives the block size.

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