From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx3.redhat.com (mx3.redhat.com [172.16.48.32]) by int-mx1.corp.redhat.com (8.11.6/8.11.6) with ESMTP id j0MDQEO14256 for ; Sat, 22 Jan 2005 08:26:14 -0500 Received: from server6.hostpoint.ch (server6.hostpoint.ch [217.26.52.16]) by mx3.redhat.com (8.12.11/8.12.11) with ESMTP id j0MDQ8Mp022207 for ; Sat, 22 Jan 2005 08:26:08 -0500 Message-ID: <41F25463.7020902@markus.org> Date: Sat, 22 Jan 2005 14:25:55 +0100 From: Markus Baertschi MIME-Version: 1.0 Subject: Re: [linux-lvm] Why the dramatic increase in filesystem performance when usingxfs???? References: <1106304669.3943.14.camel@grma-lap> In-Reply-To: <1106304669.3943.14.camel@grma-lap> Content-Transfer-Encoding: quoted-printable Reply-To: LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: Content-Type: text/plain; charset="iso-8859-1"; format="flowed" To: Gary.Mansell@ricardo.com, LVM general discussion and development If you browse through the extensive filesystem benchmarks at http://fsbench.netnation.com/ You'll find results quite similar to yours. XFS is performing well for=20 large sequential operations while ext3 without the writeback option can=20 be half the speed. I usually use ext3 for the OS volumes only, except with SuSE where=20 reiser3 is the default. For other filesystems I prefer jfs for no=20 exceptionally good reason but that I came to like it on AIX. Markus Gary Mansell wrote: > Hi, >=20 > I have always run ext3 filesystem with journalling on Redhat AS as it is > the only supported filesystem. >=20 > One of my colleagues runs xfs, though, and on comparable hardware > configs he gets twice the performance compared to my ext3 tests. >=20 > The test that I perform is to create a file at least twice the size of > the RAM installed in the system to avoid the possibility of cacheing, > measuring the time to write and read the file back gives me the > performance figure that I am after. I realise that this is a very simple > test of large sequential IO but it is good enough for my needs. >=20 > ie >=20 > Write test: >=20 > # time dd if=3D/dev/zero of=3D./testfile bs=3D16384 count=3D250000 ; time= sync >=20 > Read test: >=20 > # time dd if=3D./testfile of=3D/dev/null bs=3D16384 >=20 >=20 > As the xfs performance comes back about twice the performance of ext3 > for this test I am of the opinion that xfs must be cheating somehow. It > has always been my opinion that the IO bottleneck is the hardware and > not the filesystem hence changing the filesystem but using the same > hardware should not make a huge difference to performance (you still > have to get the same amount of data out to disk at the end of the day) >=20 > I am struggling to comprehend how xfs can cheat, though, as it can't > cache such a huge file as there is not enough memory. Is it perhaps > cheating because the file is comprised entirely of zero's? >=20 > Can someone please enlighten me >=20 > Thanks in advance >=20 > Gary Mansell --=20 Markus Baertschi Phone: ++41 (21) 807 1677 Bas du Ross=EF=BF=BD 14b Fax : ++41 (21) 807 1678 CH-1163, Etoy Email: markus@markus.org Switzerland Homepage: www.markus.org