GEOM stripe + concat
Sergey Lungu
sergey.lungu at gmail.com
Tue Jan 24 13:44:59 PST 2006
On Tue, 24 Jan 2006 15:12:58 -0600 Eric Anderson
<anderson at centtech.com> wrote:
> Sergey Lungu wrote:
> > On Sun, 22 Jan 2006 19:22:57 +0300 I wrote:
> >
> >
> >> Hello,
> >>
> >> I have FreeBSD 6.0-RELEASE running on my FTP server. There are
> >> three disks on that box: two identical 120GB and one 300GB. I am
> >> using gvinum for stripping between first two disks. I am going to
> >> give gstripe a try, sine gvinum is too unstable.
> >>
> >
> > Since nobody has answered my question, possibly it was too silly, I
> > decided to experiment a bit. I'll answer my questions:
> >
> >
> >> Am I able to concatenate created stripe with 300GB disk?
> >>
> >
> > Yes, you can!
> >
> >
> >> And is it wise at all?
> >>
> >
> > I have made some simple benchmarking on three different geometries.
> > Legend:
> > a * b - stripping between a and b
> > a + b - concatenation of a and b
> > ad1 - 120GB disk
> > ad2 - 120GB disk
> > ad3 - 300GB disk
> >
> > I tried to upload and then download a 700MB movie. Here are my
> > results:
> >
> > ad1 * ad2:
> > Uploading: 1m8.406s
> > Downloading: 1m4.656s
> >
> > ad1 * ad2 + ad3:
> > Uploading: 1m4.115s
> > Downloading: 1m4.962s
> >
> > ad1 + ad2 + ad3:
> > Uploading: 1m4.110s
> > Downloading: 1m4.971s
> >
> > Conclusion:
> > There is no big difference between all this geometries in FTP
> > context, or possibly there are some on high load!?
> >
>
> I'm not sure the details of your tests, since 'upload and then
> download' doesn't really explain the test, however I'm guessing you
> were limited by network or the destination rather than the local disk
> - 1m 4s looks alot like 100mbit to me.
Yes, we have 100mbit network.
> You should try one of the many benchmarking tools as a first start
> (try iozone, or bonnie, etc).
I'm not interested in real disk performance, since this box is used
only for ftp. Probably I was wrong from the begining and I am limited
only by the network speed, so software RAID is not the right way to
boost our ftp server :)
> Also, concat won't give you any performance increase, but striping
> could. You could easily test your 700mb file by doing something like
> this:
>
> dd if=/path/to/700mb-file of=/dev/null bs=1m
I don't think that stripping between two disks can give some
significant performance boost (I may be wrong, of course), especially
in ftp context.
I think I'll use a*b+c geometry, but the question is: Will I have the
same problems with gstripe+gconcat as with gvinum? :)
Thanks for the answer.
--
Sergey Lungu
The deficiency will never show itself during the test runs.
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