[MLUG] A mini blog about file systems.

[Stefan Monnier]

> If I have a small desktop computer with perhaps 512megs of memory and
> an 80 gig drive, what do I want to have loaded in memory so as to have
> the maximum amount of free memory available for my application?

Does anybody here have some hard-data comparing the amount of RAM
used up by various filesystems, and/or LVM?

FWIW, I'm using LVM on all my machines, except for my cellphone.
I.e. this includes my "home router" and its 64MB of RAM (driving a 1TB
drive).  Those 64MB are pretty tight, but I haven't noticed any
difference in memory pressure when I (recently) moved to LVM.

> and as little extra for the kernel.  Would EXT4 be best? That is my
> thought.

Why would ext4 be better than ext3 for this case?
Why would these same reasons not apply to a laptop?

> BTFRS in theory will replace LVM.

I don't know if/that btrfs will replace LVM.  It might be true that if
you use btrfs, you may not gain much by combining it with LVM, but btrfs
is a monster, which will tend to limit its popularity.

> Finally, in the articles I read, the new hard disks come with 16megs
> or even 32 megs of cache memory.  Not one author has been written
> about using ext[234], lvm or btfrs with these devices.

I'm not sure I understand what you wrote (I'll just assume that you
meant "article" rather than "author").  But I don't think the disk's
cache makes much difference to the choice of filesystem (there is even
little evidence that it makes much difference about anything at all:
it's important to have some cache there, used for prefetching and
write-caching, but its size is not critical: the main disk cache is in
the main memory, where it can easily grow much larger than 32MB and can
be "cheaply" increased).


        Stefan