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Top Forums UNIX for Advanced & Expert Users How to test RAID10 array performance [Debian Wheezy]? Post 302918516 by gacanepa on Wednesday 24th of September 2014 12:22:59 AM
Old 09-24-2014
Hammer & Screwdriver How to test RAID10 array performance [Debian Wheezy]?

I have created a RAID10 array (near layout) with four 8 GiB virtual hard drives, making a 16 GiB array (/dev/md0 formatted as ext4). On the other hand, I have a 16 GiB RAID1 array (/dev/md1, also formatted as ext4).
The purpose of these setups is to compare the read and write performances of each array.

So far, I have used dd to perform the following tests:

dd (sequential write performance):

Code:
    dd if=/dev/zero of=/dev/md0 count=512 bs=1024k
    512+0 records in
    512+0 records out
    536870912 bytes (537 MB) copied, 6.60623 s, 81.3 MB/s

    dd if=/dev/zero of=/dev/md1 count=512 bs=1024k
    512+0 records in
    512+0 records out
    536870912 bytes (537 MB) copied, 5.74421 s, 93.5 MB/s

dd (sequential read performance):

Code:
    dd if=/dev/md0 of=/dev/null bs=4096k
    4093+1 records in
    4093+1 records out
    17168334848 bytes (17 GB) copied, 168.665 s, 102 MB/s

    dd if=/dev/md1 of=/dev/null bs=4096k
    4093+1 records in
    4093+1 records out
    17170300928 bytes (17 GB) copied, 44.6421 s, 385 MB/s

So I changed the RAID10 array layout to f2, and sequential read performance improved but the write performance decreased compared to n2 (which was the previous layout):

Code:
    dd if=/dev/md0 of=/dev/null bs=4096k
    4093+0 records in
    4093+0 records out
    17167286272 bytes (17 GB) copied, 110.424 s, 155 MB/s

    dd if=/dev/zero of=/dev/md0 count=512 bs=1024k
    512+0 records in
    512+0 records out
    536870912 bytes (537 MB) copied, 6.84386 s, 78.4 MB/s

I was expecting that the RAID10 array would have a better read performance that that of RAID1, but it isn't the case as per these tests - even when I have performed them several times to avoid outliers. I have also used iozone for benchmarking the same setups, with similar results.

I am also aware that other factors may impact performance, such as the hardware used (perhaps virtual hard drives may not provide the best scenario?) and the filesystem.

That being said, what would be the best setup for a RAID10 array that will undergo more reads than writes? (In addition, I am looking for further reasons to use RAID10 instead of RAID1 other than the fault tolerance provided by the latter).

Any tips and ideas will be more than welcome.

Thanks in advance.
 

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pdebuild-user-mode-linux(1)					     pbuilder					       pdebuild-user-mode-linux(1)

NAME
pdebuild-user-mode-linux - pbuilder-user-mode-linux way of doing debuild SYNOPSIS
pdebuild-user-mode-linux [pdebuild-user-mode-linux options] -- [pbuilder-user-mode-linux options] DESCRIPTION
A convenience program for pbuilder-user-mode-linux which invokes pbuilder after obtaining appropriate root privilege in a Debian source directory. One must be inside the source tree containing the debian directory, in order to make it work. PDEBUILD OPTIONS
--buildsourceroot [fakeroot] The command used to gain root privilege for invoking dpkg-buildpackage --auto-debsign Invoke debsign at the end of pdebuild process. --debsign-k [key-id] Pass -k option to debsign to specify which keyid to sign. --buildresult [Directory for build results] The place which build result is stored. --configfile [Extra config file to use] The configuration file is used, but not passed on to pbuilder-user-mode-linux. --debbuildopts [options to pass to dpkg-buildpackage] The space-delimited list of options are passed to dpkg-buildpackage. This option appends to pbuilder option --debbuildopts and may also be used to reset the list of options by passing the empty string. --use-pdebuild-internal Uses a different implementation of pdebuild, which calls clean and build inside the chroot, using bind-mounts. pdebuild-internal tries to run debian/rules clean inside the chroot. To achieve the goal, the working directory is passed on inside the chroot, in the form of bind-mounting and debuild is run. This option will not protect the working directory and its parent directories from the build scripts. -- [pbuilder options] After the -- symbol, an arbitrary number of pbuilder options can be specified. See pbuilder-user-mode-linux.1 for full list of options. There is an exception that --buildresult needs to be specified as pdebuild option before the -- to be effective. FILES
/etc/pbuilderrc The configuration file for pbuilder-user-mode-linux, used in pdebuild-user-mode-linux. /usr/share/pbuilder/pbuilderrc The default configuration file for pbuilder-user-mode-linux, used in pdebuild-user-mode-linux. ${HOME}/.pbuilderrc Configuration file for pbuilder-user-mode-linux, used in pdebuild-user-mode-linux, overrides what is written in /etc/pbuilderrc AUTHOR
Initial coding, and main maintenance is done by Junichi Uekawa <dancer@debian.org>. The homepage is available at http://pbuilder.alioth.debian.org SEE ALSO
/usr/share/doc/pbuilder/pbuilder-doc.html, pbuilder-user-mode-linux(1), pbuilderrc(5), pbuilder-uml.conf(5) Debian 2006 May 24 pdebuild-user-mode-linux(1)
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