topic difference between RAW Filesystem & VxFS in Operating System - HP-UX

difference between RAW Filesystem & VxFS

Amit Dixit_2 — Tue, 10 Aug 2004 23:59:31 GMT

Hi,
Can anyone explain me the difference between
raw and vxfs filesystem.

and why and which one is good for informix
database. I know raw but dont know why ?

Thanks
Amit

Re: difference between RAW Filesystem & VxFS

Michael Tully — Wed, 11 Aug 2004 00:21:13 GMT

Raw = logical volume with no filesystem of any type. Typically they are used by databases such as informix.
vxfs filesystem is a JFS (journaled file system) that is mounted on a directory.

Informix recommends using raw logical volumes as opposed to using mounted filesystems. I think they believe it has better performance for their product.

Re: difference between RAW Filesystem & VxFS

Muthukumar_5 — Wed, 11 Aug 2004 00:27:19 GMT

A good link about raw file system why informix is using it,

http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=198966

And your profile is stating as

"I have assigned points to 78 of 402 responses to my questions."

It is good to do resolve this to get more effective responses :)

Re: difference between RAW Filesystem & VxFS

Ravi_8 — Wed, 11 Aug 2004 00:46:12 GMT

Hi Amit

Raw file system is a logicla volume without filesystem created(newfs command is not used)and is not mounted, whereas in vxfs filesystem it is defined to be vxfs type and mounted.

By the way i am observing the differences in both file systems since long back. not able to make out still.
i don't see any performance difference in these two

Re: difference between RAW Filesystem & VxFS

Trond Haugen — Wed, 11 Aug 2004 00:53:04 GMT

In HP-UX you can use LVM or VxVM to create volumes. The volumes can have no filesystem to be used as raw volumes for databases, swap or dum by the OS. Or you could create a HFS or JFS/vxfs filesystem. In which case the OS will manage the volume.

In other words:
RAW volumes are managed by the database.
Filesystems are managed by HP-UX.

Thus when having the database on a filsystem you have an extra layer (db/filesystem/volume). You don't have that when using raw volumes (db/volume).

Regards,
Trond

Re: difference between RAW Filesystem & VxFS

Jose Mosquera — Wed, 11 Aug 2004 01:44:19 GMT

Hi,

Important tip:

Data stored in raw areas needs always an export and database utility to create a a readable backup files for standard backups utilities. However, VxFS areas are directly readable for HP-UX and/or these tools.

Also, raw areas uses a character device. This transfer data blocks of variying sizes at a time without using the filesystem's I/O buffers. The user program does its own buffering.

Rgds.

Re: difference between RAW Filesystem & VxFS

Amit Dixit_2 — Wed, 11 Aug 2004 08:00:44 GMT

Hi,
What is the procedure to backup Informix
database from RAW filesyste any tool or
script to backup dbspace and logs.

Thanks,
Amit

Re: difference between RAW Filesystem & VxFS

Sanjeev gupta_2 — Wed, 11 Aug 2004 08:34:19 GMT

Hi Amit
pl. use dd command , i feel u will be able to take backup

THX
SANJEEV GUPTA