From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Evans Subject: Re: unbelievably bad performance: 2.6.27.37 and raid6 Date: Mon, 2 Nov 2009 22:09:46 -0800 Message-ID: <4877c76c0911022209g60e40364i2cb82909e31f707d@mail.gmail.com> References: <4AEEF29C.10309@tmr.com> <9e52db7bed791d8c8f5653b1958b1874.squirrel@neil.brown.name> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <9e52db7bed791d8c8f5653b1958b1874.squirrel@neil.brown.name> Sender: linux-raid-owner@vger.kernel.org To: NeilBrown Cc: Jon Nelson , LinuxRaid List-Id: linux-raid.ids On Mon, Nov 2, 2009 at 9:36 PM, NeilBrown wrote: > On Tue, November 3, 2009 2:03 am, Jon Nelson wrote: >> On Mon, Nov 2, 2009 at 8:54 AM, Bill Davidsen wro= te: >>> Jon Nelson wrote: >>>> >>>> I have a 4 disk raid6. The disks are individually capable of (at >>>> least) 75MB/s on average. >>>> The raid6 looks like this: >>>> >>>> md0 : active raid6 sda4[0] sdc4[5] sdd4[4] sdb4[6] >>>> =A0 =A0 =A0613409536 blocks super 1.1 level 6, 64k chunk, algorith= m 2 [4/4] >>>> [UUUU] >>>> >>>> The raid serves basically as an lvm physical volume. >>>> >>>> While rsyncing a file from an ext3 filesystem to a jfs filesystem,= I >>>> am observing speeds in the 10-15MB/s range. >>>> That seems really really slow. >>>> >>>> >>> >>> It is really slow, recent kernels seem to be unsuitable for use as = large >>> file servers, as the performance is, as you described it, "unbeliev= ably >>> bad." >> >> Yeah. I'm hoping that the 2.6.31.XX stable kernel series gets some o= f >> these improvements, the .27 series has been not the most stable for = me >> either. =A02.6.27.25 was the last rock-solid of the .27 series for m= e. > > I wouldn't get your hopes up... > I did some limited testing of simple writes to ext2 and the current > 32-pre kernel is noticably slower than .26 .27 .28 .29 .. (that is as > far as I got with testing... I should write a script and leave it run= ning > overnight to get a broader picture). > > NeilBrown > > -- > To unsubscribe from this list: send the line "unsubscribe linux-raid"= in > the body of a message to majordomo@vger.kernel.org > More majordomo info at =A0http://vger.kernel.org/majordomo-info.html > Maybe my speed results even after the 'fix' are also this issue: I expect each of my drives is capable of at least 8MB/sec sustained (highly pessimistic). 2909829120 blocks super 1.1 level 6, 128k chunk, algorithm 18 [8/8] [UUUUUUUU] [=3D=3D>..................] reshape =3D 10.4% (50708096/484971520= ) finish=3D3989.0min speed=3D1813K/sec The 'backup file' is on a separate raid 1 device and approximately 25 mb in size. My cpu has virtually no load and I've got gigs of memory free. (also sorry for duplicates, I hit reply at the top instead of reply to all at the bottom out of habit) -- To unsubscribe from this list: send the line "unsubscribe linux-raid" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html