[Linux-cluster] Why GFS is so slow? What it is waiting for?

[Ja S]

--- Gordan Bobic <gordan at bobich.net> wrote:

> 30K files?!
> That'll take a while even on a local file system.

Not really. Last week I made a copy of the directory
on the local hard disk (ext3). See the test results
for both "ls" and "ls -la" commands:

# time ls -la | wc -l
31767

real    0m2.967s
user    0m0.627s
sys     0m0.689s

# time ls | wc -l
31764

real    0m1.508s
user    0m0.262s
sys     0m0.082s


Comparing with the results in my previous email, does
it indicate that GFS is not designed for sharing huge
number of small files? I heard that GFS is originally
designed for sharing small number of larger files. Is
that true? If so, could you please kindly suggest a
file system which can handle huge number of concurrent
requests on many many number of small files?

Thanks for your interest.

Jas

> 
> Gordan
> 
> Ja S wrote:
> > Hi, All:
> > 
> > I used to post this question before, but have not
> > received any comments yet. Please allow me post it
> > again.
> > 
> > I have a subdirectory containing more than 30,000
> > small files on a SAN storage (GFS1+DLM, RAID10).
> No
> > user application knows the existence of the
> > subdirectory. In other words, the subdirectory is
> free
> > of accessing. 
> > 
> > However, it took ages to list the subdirectory on
> an
> > absolute idle cluster node. See below:
> > 
> > # time ls -la | wc -l
> > 31767
> > 
> > real    3m5.249s
> > user    0m0.628s
> > sys     0m5.137s
> > 
> > There are about 3 minutes spent on somewhere. Does
> > anyone have any clue what the system was waiting
> for?
> > 
> > 
> > Thanks for your time and wish to see your valuable
> > comments soon.
> > 
> > Jas
> > 
> > 
> >      
>
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