VMUNIX MESSAGES

[Nobody's Hero]

Good Morning.

Can someone explain to me why some Oracle file systems continue to consume 100% of the file system and does not complain. For example, a "vmunix error file system /xx 100% full". While other Oracle and non Oracle file systems do complain prior to reaching 100% and at 100. Does this have to do with the 'allow large file systems' option during creation of the file system?

Thanks,
Bob

[Sanjay_6 · Accepted solution]

Hi Robert,

If the filesystem is 100 full and is in use /written by some process the filesystem will send out a filesystem full message. If the filesystem is not written on, there won't be any filesystem full message. For the filesystem which are not 100% full but are sending the filesystem full message, probably the process is trying to write a file and is not finding enough space to write the file and hence sends out a filesystem full message. you can check whether the filesystem is in use or not and the processes using that filesystem by the command,

fuser -cu /mount_point

Hope this helps.

regds

[Steve Steel]

Hi

Which OS is it. You may have a disk with 0% minfree

Filesystem minfree
------------------

Every administrator has probably looked at the bdf command after
mounting a brand new disk and asked: Where did some of that empty
space go? The answer is that approximately 6% to 8% of a disk's space
is occupied by inode tables and superblocks, which contain the pointers
to the various blocks of files that are on the disk. In addition, the
default newfs command will reserve 10% minfree or 10% of what's left
before files are stored on the disk, to enhance the filesystem
performance.

This buffer allows system administrators to fix problems with the space
on a given disk (once the filesystem is marked full) and still have some
room (the 10% minfree area) to work. Although the minfree area can be
reduced to zero, this is not recommended for the root disk since a file
system full message might not allow even the system administrator to
log onto the ailing system.

Other disks might be allowed to use 0% minfree, as long as the space
is monitored, or the space usage is essentially fixed. Note also that
the HFS method of disk space management in HP-UX relies heavily on 10%
minfree to keep the performance in allocating and deallocating filespace
at a high level.



Steve Steel

[Nobody's Hero]

steve,
OS VERSION = 11.0. WHERE AND WHEN IS THE MINFREE SETTING MADE. DURING CREATION? OK, I'm still not sure why some file systems complain and others do not. I don't create any file system differently except /stand of course. So why do some complain and others do not?

[Nobody's Hero]

Steve,
My bag. where and when does 0% minfree get set

[Sanjay_6]

Hi Roberto,

Try this link to learn more about minfree and it works,

http://us-support3.external.hp.com/cki/bin/doc.pl/sid=46457afa02ed484553/screen=ckiDisplayDocument?docId=200000048161816

This value is configuratble in HFS, but seems like it is not configurable in JFS.

http://us-support3.external.hp.com/cki/bin/doc.pl/sid=46457afa02ed484553/screen=ckiDisplayDocument?docId=200000024625656

On HFS you use the "tunefs" command to configure or modify the minfree %.

Hope this helps.

Regds

[Patrick Wallek]

The difference between Oracle file systems and regular file systems is that when you create an Oracle data file, you are essentially creating a huge file that has no data in it. So your Oracle file may be 2GB at the unix level, but as for actual data in the file, you may only have 500 MB or something. So even if you write another 500 MB of data to that file, the file size at the unix level will still be 2GB, but the amount of data in the file is now 1GB.

A regular file system does not allocate files like Oracle does. It creates the file at the size it needs. So if you have a 2GB file system with 1.8GB of data and you try to create a 300MB file (total of 2.1GB) then you will start getting complaints because there is not enough room.

The file system (vmunix) will not complain until you try to write BEYOND whatever your LV size is. With Oracle, you generally never do that. This really has nothing to do with minfree, especially since minfree is not used as extensively with vxfs as it is with HFS.

HFS file systems (LVs) automatically have a 10% minfree when you create it.

Does this all make sense?

[Nobody's Hero]

Thanks, Patrick,
Yes I am happy now. Thanks for your time, you explained it well.

Bob

[Tom Dawson]

Robert,

One thing to keep in mind:

When creating an Oracle tablespace, you can
specify "Allow to grow" or "Do NOT allow to grow". If the "*.dbf" file cannot grow, it can be right at the maximum ( 100%? ) and will never get any bigger. Hence, the OS does not see an attempt to make the *.dbf file any bigger, and no warning messages get generated.

Tom

[Steve Steel]

Hi


If it is 11.00 then the minfree is not likely.

1)Please post your /etc/mnttab and indicate which disc is the problem.

2)The problem could be Oracle on this disc

If you have sparse files or a badly fragmented
disc then the system would calculate space left until it attempted to write a b lock larger than a contiguous area on the disc.

then it would give 100% disc full because it could not find place.

3)there is a newly reported problem at the labs concerning file system stats on an 11. system which is now in research and should be fixed from 11.00 later this year.


Steve Steel