20TB Storage System (fsck????)

[Andrew Kinney]

On 4 Sep 2003, at 11:53, Julian Elischer wrote:

> On Wed, 3 Sep 2003, Tim Kientzle wrote:
> 
> > Max Clark wrote:
> > > Ohh, that's an interesting snag. I was under the impression that
> > > 5.x w/ PAE could address more than 4GB of Ram.
> > 
> > That's >4G of memory in the system.  32-bit processors
> > are still limited to 4G processor address space, which means
> > <3G per process (allowing some memory for kernel operations).
> > You can't get around that unless you either go for a 64-bit
> > processor or do some complex coding to break your application
> > storage across multiple processes.
> 
> 
> It's worse than that, becasue I think that to handle >4GB of ram you
> need to limit your processes to about 2G of virtual space.
> 

Our experience has been that with 4GB of RAM (or more) you 
really must increase your KVA to 2GB, leaving only 2GB of UVA.  
So, I would concur with what Julian said.

<ducks his head to avoid the rotten tomatoes that are sure to be 
thrown> ;-)

With the lack of third party filesystem support in FreeBSD, might 
you be better served by looking at a Linux system running 
ReiserFS or one of the other file systems designed for such 
behemoth disk systems?

These days, I think Sun even gives away Solaris licenses with their 
low end x86 servers, so that might even be an option.

UFS is great, but there are other filesystems out there that have 
already addressed such problems from their use in academic, 
government, and scientific computing where gigantic filesystems 
tend to be more prevalent.

>From my brief research on the subject, the FreeBSD community 
has been highly resistant to supporting third party filesystems 
precisely because nobody with such needs as yours has ever 
contributed the code necessary to make third party filesystem 
support a reality.  The response is usually something like "if you 
want it, go program it and submit it to a committer for review," 
which is really the only reasonable response that can be made 
given FreeBSD's goals.

C'est la vie.

Sincerely,
Andrew Kinney
President and
Chief Technology Officer
Advantagecom Networks, Inc.
http://www.advantagecom.net