sparse file system

[Shivkumar]

What is sparse file system ? Does core files contain holes ?

Thanks,
Shiv

[Adisuria Wangsadinata_1]

Hi Shiv,

Check the url below (docID : KBAN00001035) about 'sparse file explanation and identifying sparse files' :

http://www2.itrc.hp.com/service/cki/docDisplay.do?docLocale=en_US&docId=200000077186715

Hope this information can help.

Cheers,
AW

[Devender Khatana]

Hi,

There is no such file system type in HPUx. It is a file system type for MS Windows XP & Win2k.

HTH,
Devender

[Adisuria Wangsadinata_1]

Hi Shiv,

Here is the additional information (docID : A5329700) about 'File System: Sparse file tutorial' :

http://www2.itrc.hp.com/service/cki/docDisplay.do?docLocale=en_US&docId=200000080024165

Hope this information can help you.

Cheers,
AW

[Pete Randall]

Never heard of sparse file systems (aren't they all until you put some data in them?). There are sparse files, though:

http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=690868


Pete

[Robert-Jan Goossens]

Like the others said, ther is no sparse filesytem.

Chech the prealloc command

# prealloc myfile 50000
will give you sparse file of 50000 byte.

Regards,
RJ

[Victor BERRIDGE]

Hi Shiv,

The only case I know of mention of sparce file system is under AIX:
"The straightforward solution to these problems is to make a private copy of a single, read-only,master disk image before each simulation. Despite the efficiency of AIX's sparse file system, these

disk images may easily grow to the full size of the simulated disk, quickly filling the host filesys-tem. "

"NetView databases in UNIX are what are known as a sparse file system. The
items in them are pointed to by pointers in a directory file. Typically
these are widely spaced numerically. When the untar occurs, tar actually
allocates file space for all the entries between the existing pointers,
space which may never be used. Because of this we have always recommended
that when you restore, you use pax rather than tar, because pax is smart
enough to understand the sparse file system and not use more space than he
needs. Of course, if you have a lot of disk space this is not an issue,
and with the use of nvTurbodatabase, which now automatically compresses the
sparse files on startup, the whole thing is probably moot. I haven't
looked into it in quite a while.

But if you are on an older version or you just want to play safe and save
your disk space, if you do, for example,
tar -cvf mybakup.tar /usr/OV/databases/openview
to create your backup, then do
pax -rp e -f mybakup.tar
to restore it.


James Shanks
Level 3 Support for Tivoli NetView for UNIX and Windows
Tivoli Software / IBM Software Group"

Why?
Unix filesystems tend to have special support for sparse files: they donâ t allocate
disk blocks for blocks that have never been written to.

All the best
Victor

[Yogeeraj_1]

hi,

below my experience with sparse files.

For our Oracle Database, we use locally managed temporary tablespaces created using "CREATE TEMPORARY TABLESPACE" command - not just alter a permanent tablespace to a temporary one.

One of the nuances of true temporary files is that if the operating system permits it â the temporary files will be created â sparseâ . That is, they will not actually consume disk storage until they need to.

i will try to see if i can prepare a "demo"..

hope this helps!
regards
yogeeraj