[ILUG] Reiserfs storage efficiency

[Niall O Broin]

On Sat, Dec 30, 2000 at 03:13:30PM +0000, Wesley Darlington wrote:

> Incidentally, I believe patches from about 3.5.25 onwards switched to
> making filesystems using the `r5' hash, by default. Not sure what the
> benefits/differences are between it and `tea' (IIRC)...?

I now have the box running 2.2.18 with reiser 3.5.29 and having read the FAQ
I decided to check the usage out with df, so I simply used the original 1G
disk and made a Reiser FS on the relevant partition and I got the following
results from df (slightly modified to show FS type instead of partition)


Filesystem           1k-blocks      Used Available Use% Mounted on
ext2                    999614    977701     21913  98% /mnt

Filesystem           1k-blocks      Used Available Use% Mounted on
Reiser 3.5.23          1032828    980324     52504  95% /mnt

Filesystem           1k-blocks      Used Available Use% Mounted on
Reiser 3.5.29          1032828    981448     51380  95% /mnt


The exact same tree of files is on each filesystem and as you can see, the
situation does not look nearly as bad with df as it did with du BUT Reiser
still uses a little more disk space than ext2, and it seems that the r5 hash
as used in 3.5.29 is slightly worse than the tea hash as used in 3.5.23.
This set of files should have been a perfect opportunity for Reiser to show
off its better usage with small files, as there are about 125000 files there
between 1K and 2K, but it certainly isn't any better. Of course I'm not
about to cry over the space used, but I am curious. Perhaps I'd better join
the Reiser mailing list.





Regards,


Niall