Re: CCL:Linux 2.4.0 and 2 GB promlem
Jonas Juselius wrote:
>
> The 2GB limit is a thing of the past in 2.4.1, but you must use ReiserFS
> (or XFS from SGI) to get past the limit. AFAIK ext2 does still not handle
> files larger than 2GB. I have been using ReiserFS together with LVM
> (www.sistina.com) for some time now, and I'm extermely happy with the
setup.
> If I do a one finger boot, the filesystem check on my 25 GB work partition
> (ReiserFS) takes about 2-3 seconds :-)
>
> -jonas-
This statement is not correct. We operate a 3.5 GB
single file database successfully under Linux2.4
on an ext2 filesystem.
However, there are a number of issues which we observed
in our SuSE7.0 distribution setup (some of these
problems may be resolved in newer releases, SuSE 7.0 contains
a prerelease 2.4 kernel)
a) quota support is broken
b) regardless of user limit settings, only root can actually write
files larger than 2 Gb. Otherwise, a file size exceeded
signal will be generated and no bytes are written.
c) ftell64() will return negative position values if the
file pointer is beyond 2Gb, regardless of compilation flags.
Add 4Gb to compensate if the value is negative (and of course
use int64_t/off64_t vars for this kind of arithmetic). I don't
know what happens if your file is larger than 4Gb.
d) Accroding to our measurements,
the performance of mmap64()ed memory from
extended segments of a big file is atrocious
and leads to severe paging, even if only
a small section of the mapped area is actually touched.
The vmem memory page swapping mechanisms desparately require
improvements for this kind of application
(IRIX does much better with the same software)
--
Dr. Wolf-D. Ihlenfeldt
Computer Chemistry Center, Institute for Organic Chemistry,
University of Erlangen-Nuremberg
Naegelsbachstrasse 25, D-91052 Erlangen (Germany)
Tel (+49)-(0)9131-85-26579 Fax (+49)-(0)9131-85-26566
http://www2.ccc.uni-erlangen.de/wdi/