[linux-lvm] lvm partition on ramdisk

[Stuart D. Gathman]

On Tue, 13 May 2008, Larry Dickson wrote:

> on the full, unpartitioned lv. Then it mounted, with the entire FAT on
> ramdisk, and wrote very fast because FAT32 (like DOS) lays down data in
> order from the start of a disk and does not skip around (I'd be interested
> if anyone knows any other file systems with that property).

The SysV filesystem put a fixed size inode table at the beginning of a
partition.  More modern filesystems from ext to reiser try to distribute
the meta-data to keep it closer to the data.  This is, of course, counter
productive when the beginning of a disk is significantly faster and seek-free
as in your setup.  

Since ext3 inode placement is table driven (with the table in a magic inode),
there is probably a simple patch to mke2fs to create only one inode table at
the beginning of a drive.  In fact, I wonder if there is already an option...
looks like -g blocks_per_group might do the trick - assuming inodes are 
at the beginning of a block group, rather than the middle.  If not,
a patch to mke2fs is needed to do what you want.

-- 
	      Stuart D. Gathman <stuart at bmsi.com>
    Business Management Systems Inc.  Phone: 703 591-0911 Fax: 703 591-6154
"Confutatis maledictis, flammis acribus addictis" - background song for
a Microsoft sponsored "Where do you want to go from here?" commercial.