fstab Doubt

[unixguy_1]

Hi Friends,

In Our HP-Unix Server, i edited that fstab entry,it's howing below mentioned things,

"/dev/vg02/lv014 /opt/newdata vxfs delayed 0 2"

1.Here what's meaning of "delayed"?

actually what's does it mean?

2.Here,last one "0 2" sometime "0 1" ,what does it mean?

Pls anyone guide me brief explanation.

Thanks in advance.

Regards,
Unixguy.

[Jozef_Novak]

Try:

# man fstab

I suppose that "delayed" is somehow mistyped, should be "delaylog" instead, which is one of vxfs mount options.

J.

[unixguy_1]

Hi Friends,

Iam not able tounderstand.

Any one help to me.

Regards,
Unixguy.

[Robert-Jan Goossens_1]

Hi,

the delayed option does not exist! Have a look at the mount_vxfs(1m) manual. There is a delaylog option, so possibly someone mistyped the delaylog option.

---
In delaylog mode, some system calls return before the intent log is written. This improves the performance of the system, but some changes are not guaranteed until a short time later when the intent log is written. This mode approximates traditional UNIX system guarantees for correctness in case of system failures.
---
Robert-Jan

[Ganesan R · Accepted solution]

Hi Unixguy,

>>Here,last one "0 2" sometime "0 1" ,what does it mean?<<<

These numbers are called "backup frequency" and "pass number" .

This is the explanation for these parameters.

backup frequency:
-----------------
Reserved for possible use by future backup utilities.

pass number :
--------------

Used by the fsck command to determine the order in which file system checks are done. The root file system should be specified with a pass number of 1, to be checked first, and other file systems should have larger numbers. (A file system with a pass number of zero is ignored by the fsck command.)

File systems within a drive should be assigned different pass numbers, but file systems on different drives can be checked on the same pass, to utilize possible parallelism available in the hardware. If pass number is not present, fsck checks each such file system sequentially after all eligible file systems with pass numbers have been checked.

Hope you understand now.

[Duncan Edmonstone]

There was a "delayed" option on the hfs filesystem (see "man 1m mount_hfs" for details) which ensured buffered writes to disk. Assuming the filesystem really is a vxfs filesystem and not a hfs filesystem (check with "fstyp /dev/vg02/rlv014") then that option means nothing. You would get roughly equivalent behaviour on a vxfs filesystem by default anyway (i.e. buffered writes)

HTH

Duncan

[~sesh]

The delay option may exist for use with network (NFS) mounts. Or for buffered / cached writing to the disks.

However this option you have specified does not seem relevant to the vxfs file system you are using.

[unixguy_1]

Hi Friends,

I understand.

Hi ganesan,

Thnaks for your Answer and one thing is what about that delayed.

actually what does it mean.

can u please guide me something.

Regards,
Unixguy.

[Duncan Edmonstone]

As I explained in my post the "delayed" mount option is a mount option for a hfs filesystem - if this is really a vxfs filesystem then the option means nothing. Check what type of filesystem ut is by running:

fstyp /dev/vg02/rlv014

If it's vxfs you might as well get rid of the "delayed" option as it doesn't mean anything. If the filesystem is hfs you need to change the entry in fstab to read:

/dev/vg02/lv014 /opt/newdata hfs delayed 0 2

If you want to know what the "delayed" option means look at the man page for mount_hfs

HTH

Duncan

[unixguy_1]

Hi Friends,

i got it.

Thanks for your support.

Regards,
Unixguy.