dan schrieb:

(...)

> on a side note, i did some rudementary benchmarks on an ubuntu 7.10 
> server install and a freebsd7 install in vmware server.  UFS was about 
> 10% slower than ext3 in creating 10,000 directories and about 20% slower 
> at creating 10,000 hard links to 1 file(same *virtual hardware, virtual 
> hardware leaves some margin for error though).  I watched TOP and IOSTAT 
> on both systems and the disk was definitely the only resource being 
> consumed that would effect performance.  I did the same test on ZFS and 
> it was 20x faster than UFS at creating hardlinks and 50x faster at 
> creating directories BUT consumed ~200MB of ram doing it.

50x times faster is a *very* big difference and it's hard to believe 
it's actually true.

Are you sure everything was committed (synced) to the disk in all these 
cases?

 From what you write, it sounds as if with ZFS everything was still 
purely in RAM (large RAM usage and 50x faster).

It is fine when you do an operation like that once in a while, but with 
BackupPC, ~random reads and writes are being made basically ~24h/day, 
which means pressure on RAM sooner or later.


-- 
Tomasz Chmielewski
http://wpkg.org


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