how to determone the block size in a jfs filesystem and how to know if large file size is enabled

[khilari]

Hi guys, i wanted to know as to how do i determine the block size in a filesystem (vxfs) when working with Oracle it is needed). Secondly, i know when u make a file system u put the -o option for lareg file sizes but how do u check afterwards that it is enabled.
Thanks

[Sandman!]

Use the mkfs(1M) cmd to determine the blocksize and the largefiles setting on a particular filesystem. For ex. if the FS is mounted on "/dev/vgXX/lvolNN" then...

# /usr/sbin/mkfs -F vxfs -m /dev/vgXX/lvolNN

[Todd McDaniel_1]

If you want to find out if largefiles is enabled.

# fsadm -F vxfs /path/to/filesystem

If you want to find the block size look at the vgdisplay output under "PE size"

[A. Clay Stephenson]

LVM has nothing to do with filesystem blocksize so vgdisplay is meaningless for this. If you are concerned about filesystem blocksize and how it might impact database block size then answer for vxfs filesystems is that it doesn't matter because vxfs filesystems are extent-based rather than block-based. This means that the filesystems always tries to write in large chunks regardless of the block size. Block size does matter in hfs/ufs filesystems but if you are concerned about performance, you would never run a database under those filesystem flavors.

[Todd McDaniel_1]

ahh my bad, I read too fast on the block size part.

no points on this post.

[James George_1]

Hi

Here is another way to check the large files. see the command and the output. If the f_flag is set to 16 , large file is activated. If set to 0 , then large files not supported. Also see the f_blocksize ..



# fstyp -v /dev/vg21/lvol1

vxfs
version: 4
f_bsize: 8192
f_frsize: 1024
f_blocks: 1024000
f_bfree: 530841
f_bavail: 497920
f_files: 132228
f_ffree: 132708
f_favail: 132708
f_fsid: 1073938433
f_basetype: vxfs
f_namemax: 254
f_magic: a501fcf5
f_featurebits: 0
f_flag: 16
f_fsindex: 7
f_size: 1024000


Rgds / James George

[Tom Danzig]

To determine block size and largefiles enabled (for / in this example):

fstyp -v /dev/vg00/lvol3
vxfs
version: 3
f_bsize: 8192
f_frsize: 1024 <-- this is the block size of the file system
f_blocks: 524288
f_bfree: 414238
f_bavail: 388361
f_files: 139348
f_ffree: 103556
f_favail: 103556
f_fsid: 1073741827
f_basetype: vxfs
f_namemax: 254
f_magic: a501fcf5
f_featurebits: 0
f_flag: 0 <-- this will be 16 if largefiles enabled
f_fsindex: 6
f_size: 524288