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Re: To ext3 or not to ext3?


On Tue, Jul 10, 2001 at 11:55:26AM -0600, Joel Votaw wrote:
> Are there any known issues with:
> 	- LVM
> 	- LVM snapshots (more on that in a sec)
> 	- Software RAID 5
> 	- knfsd (including NFS v.3 support)

No.  It should all work --- if it doesn't, please let me know!

However, we are getting reports of lockups under severe VM load.  It
seems reproducible on ext2 too (especially on HIGHMEM machines), but
ext3 drives the VM a bit harder by requiring more memory allocations
internally for some operations and by imposing extra synchronisation
between filesystem syscalls.

I'm still hunting this --- it looks like ext3 is just making the VM
suffer more, rather than producing any genuine new bugs.  There are
still lots of patches going into the 2.4 core VM to try to help.

> I think that ext3 support for LVM snapshots is still in the works... I'm
> okay with not using them until they work, but would still like to plan
> ahead and put the filesystem on an LVM volume now.

They should work straight away, although it's not something I've
played with myself.

> Also, my understanding from the various benchmarks posted around is that
> ext3 and reiserfs are neck-and-neck in terms of speed.  Reiserfs may have
> a slight advantage but I'd rather put my trust in ext3 given past
> experiences.  Does that sound reasonable and accurate?

Sort of.  ext3 seems to suffer less from fragmentation over time and
performs better for some large-file tasks such as database file
access; reiserfs is obviously known to be faster on huge directories
and has better efficiency on small files.  However, most normal users
probably won't notice much difference between them.


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