20TB Storage System (fsck????)

[Max Clark]

Ohh, that's an interesting snag. I was under the impression that 5.x w/ PAE
could address more than 4GB of Ram.

- The PAE support allows FreeBSD machines to make use of more than 4
gigabytes of RAM. This functionality was originally written by Jake
Burkholder under contract with DARPA and Network Associates Laboratories.
Additional changes for individual device drivers will follow in the coming
weeks.

If fsck requires 700K for each 1GB of Disk, we are talking about 7GB of Ram
for 10TB of disk. Is this correct? Will PAE not function correctly to give
me 8GB of Ram? To check 10TB of disk?

Is there anyway to bypass this requirement and split fsck into smaller
chunks? Being able to fsck my disk is kinda important.

I have zero experience with either itanium or opteron. What is the current
status of support for these processors in FreeBSD? What would the preferred
CPU be? Will there be PCI cards that I would not be able to use in either of
these systems?

Thanks,
-Max

-----Original Message-----
From: Petri Helenius [mailto:pete at he.iki.fi]
Sent: Wednesday, September 03, 2003 10:13 AM
To: Max Clark
Cc: Dan Nelson; freebsd-performance at freebsd.org
Subject: Re: 20TB Storage System


Max Clark wrote:

>- What exactly is the fsck problem? What do I do about it?
>
>
>
fsck requires approximately 700k memory for each gigabyte of disk space.
I´m unfortunately not familiar enough with the issue how this splits out
for
blocks and inodes (for example if having only a million inodes on a 10TB fs
would make it tolerable) but taking the figure presented earlier, you would
need 7GB of memory for checking a 10TB filesystem. Having that kind
of memory for a single process neccessiates a 64bit system, like sparc64,
alpha, itanic or opteron.

Pete