Hi,
On Fri, 16 Feb 2007, Andi Kleen wrote:
If you stripe two disks with a standard fs versus use one of them
as metadata volume and the other as data volume with dualfs i would
expect the striped variant usually be faster because it will give
parallelism not only to data versus metadata, but also to all data
versus other data.
If you have a RAID system, both the data and meta-data devices of DualFS
can be stripped, and you get the same result. No problem for DualFS :)
Sure, but then you need four disks. And if your workloads happens
to be much more data intensive than metadata intensive the
stripped spindles assigned to metadata only will be more idle
than the ones doing data.
Stripping everything from the same pool has the potential
to adapt itself to any workload mix better.
Why do you need four disks? Data and meda-data devices of DualFS can be on
different disks, can be two partitions of the same disk, or can be two
areas of the same partition. The important thing is that data and
meta-data blocks are separated and that they are managed in different
ways. Please, take a look at the presentation (see below).
I can see that you win for some specific workloads, but it is
hard to see how you can win over a wide range of workloads
because of that.
No, we win for a wide range of common workloads. See the results in the
PDF (see below).
Also I would expect your design to be slow for metadata read intensive
workloads. E.g. have you tried to boot a root partition with dual fs?
That's a very important IO benchmark for desktop Linux systems.
I do not think so. The performance of DualFS is superb in meta-data read
intensive workloads . And it is also better than the performance of other
file system when reading a directory tree with several copies of the Linux
kernel source code (I showed those results on Tuesday at the LSF07
workshop)
PDFs available?
Sure:
http://www.ditec.um.es/~piernas/dualfs/presentation-lsf07-final.pdf
Is that with running a LFS style cleaner inbetween or without?
'With' a cleaner.
I would be interested in a "install distro with installer ; boot afterwards
from it" type benchmark. Do you have something like this?
-Andi
I think that the results sent by Sorin answer your question :-)
Regards,
Juan.
--
D. Juan Piernas Cánovas
Departamento de Ingeniería y Tecnología de Computadores
Facultad de Informática. Universidad de Murcia
Campus de Espinardo - 30080 Murcia (SPAIN)
Tel.: +34968367657 Fax: +34968364151
email: [email protected]
PGP public key:
http://pgp.rediris.es:11371/pks/lookup?search=piernas%40ditec.um.es&op=index
*** Por favor, envíeme sus documentos en formato texto, HTML, PDF o PostScript :-) ***
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