Sybase dump file size limitation

[Mike Hassell]

It seems that our Sybase DBAs have been dumping the database by striping it to mutiple files to a mounted filesystem to overcome the 2GB limitation that exists on HP-UX 10.20.

Today they are running into this limitation again and I'm having problems finding the proper information. It is my understanding that HP-UX 10.20 supports a max file size of 128GB as well as max file system size of 128GB. I have a 40GB dump area for the DBAs to perform the dumps to, where the database is broken up into 2GB segments (stripes).

I have enabled support for largefiles via fsadm on this vxfs mounted file system, but I'm still running into one issue and that is, what about ulimit?

The sybase user is using the ksh shell, which shows a ulimit of:

-----------
$ ulimit
4194304
$
-----------

Which should be 2GB. How do I overcome this limitation so the sybase user can dump the database to one big flat file? The only other tricky thing that comes into play is that the dump area is NFS mounted to other servers and used for dumping multiple databases, due to lack of diskspace.

I've looked into removing this max file size limitation and it's easy for AIX (/etc/security/limits file), but it appears to be hardcoded in the kernel for HP-UX. Do I have to recompile/install Sybase to take advantage of this largefiles option or can I somehow bump up the ulimit so they can dump these large files to disk?

--------------------
HP-UX 10.20
Sybase ASE 11.0.3.2
--------------------

Thanks,
- Mike

[Chin Guan · Accepted solution]

Hi Mike, I think you cannot dump file > 2GB via NFS file system. That's the limitation of HP-UX 10.20.


Doc id A4798375
NFS: Filesize/filesystem specifics through 10.20
.......
In fact, even a 10.20 NFS client cannot create a file larger than 2Gb over an NFS ountpoint. A 10.20 system can create a local file as large as 128Gb, but NFS large file support is not available.


Doc id UNX1030234
Support for large files, UIDs, GIDs over NFS at HP-UX 10.20?

Large Files
-----------
At 10.20, HP-UX supports files up to 128GB in size. The prior limit was 2GB. Any file greater than 2GB is considered a large file.
Large files are supported through a new set of system calls and libc routines, as well as through HP-UX system administration and user commands.

The implementation is supported on UFS (HFS) and JFS Version 3 file systems, but not on NFS or JFS Version 2 file systems. In addition, the
implementation is completely binary compatible with prior releases of HP-UX.

For a complete description of the HP large file implementation, refer to the HP-UX 10.20 Large Files White Paper /usr/share/doc/lg_files.txt
(ASCII text version) or /usr/share/doc/lg_files.ps (PostScript version).

[Mike Hassell]

Chin,

Thanks for all the documentation, I figured NFS would cause some limitations.

So if I create a mounted vxfs filesystem that is local to the server and enable largefiles support via fsadm, then will ulimit cause problems if a user who has the ksh shell tries to create a file larger than 2GB?

It is my understanding that the version of Sybase we are currently running does not support making the OS calls to create64, lseek64, etc. So in this case, it really wouldn't matter, but I would like to know if it's possible if the applicaton did support the use of these OS calls? Any ideas? Thanks.

- Mike

[Chin Guan]

Hello Mike,
A normal user with ksh and ulimit shows 4194304 has no problem creating files > 2GB in a vxfs file system with largefiles option turn on. I have tested this on my 10.20 machine.

For your second question, I am afraid I am cannot help much, may be u can post the question to the language group.