FW: 20TB Storage System
phk at phk.freebsd.dk
Tue Sep 2 13:01:49 PDT 2003
In message <ILENIMHFIPIBHJLCDEHKIEMEDCAA.max.clark at media.net>, "Max Clark" writ
>Given the above:
>1) What would my expected IO be using vinum to stripe the storage enclosures
That depends a lot on the applications I/O pattern, an I doubt a
precise prediction is possible.
In particular the FibreChannel is hard to predict the throughput off
because the various implementations seems to have each their own
peculiar quirks performance wise.
On a SEAGATE ST318452 disks, I see sequential transfer rates
at the outside rim of the disk of 58MB/sec. If I stripe two of
them them with CCD I get 107MB/sec.
CCD has a better performance than Vinum where they compare.
RAID-5 and striping a large number of disks does not scale linearly
performance wise, in particular you _may_ see your average access
time drop somewhat, but there is by far no guarantee that it will
be better than the individual drive.
>2) What is the maximum size of a filesystem that I can present to the host
>OS using vinum/ccd? Am I limited anywhere that I am not aware of?
Good question, I'm not sure we currently know the exact barrier.
>3) Could I put all 20TB on one system, or will I need two to sustain the IO
Spreading it will give you more I/O bandwidth.
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
More information about the freebsd-hackers