Bogus LBD patch

Bogus LBD patch

[Peter Chubb]

Hi,
	The patch at the URL I just posted doesn't work.  Blame my
poor handling of bitkeeper --- some changes seem to be missing.

I'll get a new patch up asap.

--
Dr Peter Chubb				    peterc@gelato.unsw.edu.au
You are lost in a maze of BitKeeper repositories, all almost the same.

RE: Bogus LBD patch

[Peter Chubb]

>>>>> "AmitR" == Amit Agrawal <Amit> writes:

AmitR> Hi Peter I've been found in your todo list ,in url u have
AmitR> given, that "large disc simulator" is planned, there is one
AmitR> solution developed by me regarding this,which ignores filedata
AmitR> and writes only metadata on the actual device so a large disc
AmitR> space is seen especially for big files. This produces a real

That sounds like a good idea.

AmitR> "large disc simulator" in you todo list.Please tell me your
AmitR> strategy for "large disc simulator" , if you have planned it

What I did was create a fake scsi device based on the HP simulator for
IA64, backed by a sparse file.  So it's really a loop device that
obeys SCSI commands.  It worked back on 2.5.9, but the changes since
then mean it deadlocks immediately now --- I intend to fix it, and
release it as soon as I can make some time.

The purpose was to test the SCSI layer's response to large discs.

What I'm trying to test now is what happens with real discs. 
I found that ext2 has too much metadata for the amount of disc space I
have for the sparse file approach to work.  JFS worked very well.
Reiserfs doesn't work at present, but I sent the bug report to them,
and they're working on the problems.

The testing I'm doing is:
    1.  Is the size of the drive reported correctly by the kernel?
	-- at bootup
	-- via ioctl(GETBLKSIZE)
	-- via ioctl(GETBLKSIZE64)
	-- via lseek(,0, SEEK_END)
    2.  Can the drive be partitioned?
        I expect Gnu parted with GDT to work properly; I expect the
	others to fail gracefully
    3.  Can a file system be written to the drive?
        I've been testing ext2, jfs and reiserfs;
	I tested XFS on an earlier patch, but at present it's too much
	of a pain to integrate.
    4.  If a filesystem is created, does fsck work?
    5.  Can the filesystem be mounted?
    6.  Then test how large a file I can create on the filesystem,
        both sparse and full.

--
Dr Peter Chubb				    peterc@gelato.unsw.edu.au
You are lost in a maze of BitKeeper repositories, all almost the same.

Re: Bogus LBD patch

[Andreas Dilger]

On Jun 25, 2002  16:59 +1000, Peter Chubb wrote:
> I found that ext2 has too much metadata for the amount of disc space I
> have for the sparse file approach to work.

You can easily change this by reducing the number of inodes created.
If you specify "mke2fs -N 1 <dev>" you will get the minimum possible
number of inodes created.  There is currently a 16TB limit on ext2/3
filesystems, unless you are testing on a platform with 8kB+ PAGE_SIZE
and have the e2fsprogs from the BK repository, in which case you can
create 8kB blocks (for 32TB filesystems).

Cheers, Andreas
--
Andreas Dilger
http://www-mddsp.enel.ucalgary.ca/People/adilger/
http://sourceforge.net/projects/ext2resize/