From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lists.gentoo.org ([140.105.134.102] helo=robin.gentoo.org) by nuthatch.gentoo.org with esmtp (Exim 4.62) (envelope-from ) id 1HdWc0-0004gY-Ex for garchives@archives.gentoo.org; Mon, 16 Apr 2007 19:11:41 +0000 Received: from robin.gentoo.org (localhost [127.0.0.1]) by robin.gentoo.org (8.14.0/8.14.0) with SMTP id l3GJ9srU005619; Mon, 16 Apr 2007 19:09:54 GMT Received: from megahappy.net (82-182-31-216.static.tierzero.net [216.31.182.82]) by robin.gentoo.org (8.14.0/8.14.0) with ESMTP id l3GJ3GxN028372 for ; Mon, 16 Apr 2007 19:03:17 GMT Received: from [10.111.23.189] (unknown [208.49.103.6]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by megahappy.net (Postfix) with ESMTP id 814F54C00D for ; Mon, 16 Apr 2007 11:59:38 -0700 (PDT) Message-ID: <4623C8D5.6000104@megahappy.net> Date: Mon, 16 Apr 2007 12:04:53 -0700 From: Bryan Whitehead User-Agent: Mozilla Thunderbird 1.0.7 (Windows/20050923) X-Accept-Language: en-us, en Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-user@gentoo.org Reply-to: gentoo-user@lists.gentoo.org MIME-Version: 1.0 To: gentoo-user@lists.gentoo.org Subject: Re: [gentoo-user] RAID-0 with LVM - is there any point? References: <20070401211824.70fb75f9@krikkit.digimed.co.uk> <4611CB98.6060800@ilievnet.com> <20070403084738.7015c9ea@krikkit.digimed.co.uk> <46150A0A.4090305@ilievnet.com> In-Reply-To: <46150A0A.4090305@ilievnet.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Archives-Salt: 1a1dea98-b833-4ca6-bda2-c65455cdb23a X-Archives-Hash: 2cfaf90569f2953d91836075843be2cd I think you need to try running a real benchmark like bonnie++ against both. For example, you run "time dd" but you don't include the "sync" in the time... Daniel Iliev wrote: >Neil Bothwick wrote: > > >>Hello Daniel Iliev, >> >> >> >> >>>Actually I'd be glad to read some results from a "Fake RAID-0 vs LVM" >>>tests. My bet would be that RAID-0 w/o LVM would give the best speeds >>> >>> >>> >>Omitting LVM isn't an option, I'd lose all the flexibility that LVM >>offers. I don't see why RAID-0 should be necessarily more efficient than >>LVM, unless there's something superior about RAID-0's striping >>algorithms. I could do some before and after tests, but I'd first have the >>reformat the filesystems to remove any effects of fragmentation. >> >>If no one comes up with a good reason for keeping the RAID, I'll get rid >>of it, running bonnie++ before and after. >> >> >> >> >> > >Hi, Neil! > >Out of curiosity I made some tests which confirmed my expectations. What >about you - did you have time (and wish) to take some performance >benchmarks? I would be glad to see some additional results. > >I'm attaching my tests in file called "bench.txt". > > > > >------------------------------------------------------------------------ > >echo y | mdadm -C /dev/md9 -n2 /dev/sda11 /dev/sdb11 -l0 >mkfs.xfs /dev/md9 >mkdir /test >mount /dev/md9 /test >dd if=/dev/urandom of=/test.rnd bs=1M count=1500 > >time cp /test.rnd /test >real 0m44.981s >user 0m0.036s >sys 0m6.967s > >sync > >time mv /test.rnd /test >real 0m47.514s >user 0m0.047s >sys 0m7.077s > >sync > >time mv /test/test.rnd / >real 0m53.863s >user 0m0.060s >sys 0m8.885s > >mdadm --stop /dev/md9 >pvcreate /dev/sda11 >pvcreate /dev/sdb11 >vgcreate test /dev/sda11 >vgextend test /dev/sdb11 >vgdisplay | grep 'Total PE' > Total PE 1686 >lvcreate -i2 -l1686 -nlogvol test >mkfs.xfs /dev/test/logvol >mount /dev/test/logvol /test > > >time cp /test.rnd /test > >real 1m12.183s >user 0m0.039s >sys 0m9.570s > >sync > >time mv /test.rnd /test > >real 0m51.643s >user 0m0.044s >sys 0m7.275s > >sync > >time mv /test/test.rnd / > >real 1m54.937s >user 0m0.047s >sys 0m9.556s > > >================= >BOTTOM LINE: > >cp /test.rnd /test >LVM: 20.78 [MB/s] >RAID-0: 33.41 [MB/s] > >mv /test.rnd /test >LVM: 29.04[MB/s] >RAID-0: 31.56[MB/s] > >mv /test/test.rnd / >LVM: 11.11[MB/s] >RAID-0: 27.84[MB/s] > >Strange: I repeated the last LVM test because it seemed to me as a low performance peak, but the result was again very low: >time mv /test/test.rnd / > >real 1m27.775s >user 0m0.050s >sys 0m9.813s > >which is: 1500/87.775 = 17.089 [MB/s] > -- gentoo-user@gentoo.org mailing list