From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: Re: Device utilization with RAID-1 Date: Fri, 19 Aug 2011 10:31:35 +1000 Message-ID: <20110819103135.5b6a3998@notabene.brown> References: <4E4C5C29.6040303@googlemail.com> <20110818114205.61aaa454@notabene.brown> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: CoolCold Cc: hochglanz@googlemail.com, hochglanz@gmail.com, linux-raid@vger.kernel.org List-Id: linux-raid.ids On Thu, 18 Aug 2011 17:44:19 +0400 CoolCold wro= te: > On Thu, Aug 18, 2011 at 5:42 AM, NeilBrown wrote: > > On Thu, 18 Aug 2011 02:26:17 +0200 Harald Nikolisin > > wrote: > > > >> hi, > >> > >> I didn't want to complain in general about SW RAID-1 performance. = I > >> simply think something is wrong with my setup and I have currently= no > >> idea how to improve. > >> > >> The basic questions (where I did not find an answer, neither in FA= Q's > >> nor in forum discussions) are. > >> a) Is it normal that the hard drives show an permanent utilization > >> (around 20%) without any noticeable actions on the computer? > > > > No. =A0If the array is resyncing or recovering then you would expec= t > > utilization for as many hours as it takes - but that would show > > in /proc/mdstat. > > > >> b) Should (as long as no resync happens) the state of mdadm active= or clean? > > > > If anything has been written to the device in the last 200msec (inc= luding > > e.g. access time updates) then expect it to be 'active'. > > If nothing has been written for 200msecc or more, then expect it to= be clean. > > > > If you crash while it is active, a resync is needed. > > If you crash while it is clean, no resync is needed. > > If you don't crash at all .... that is best :-) >=20 > I think this info should be wikified if not yet. >=20 > btw, I've experimented a bit on my /boot array (it doesn't being > updated, checked with iostat ), and: > root@m2:~# for i in {1..5};do mdname=3D"md0"; echo "iteration $i"; > (mdadm --detail /dev/$mdname|grep 'State ';cat > /sys/block/$mdname/md/array_state;grep "$mdname :" /proc/mdstat);slee= p > 1;done > iteration 1 > State : clean > clean > md0 : active raid1 sda1[0] sdb1[1] > iteration 2 > State : clean > clean > md0 : active raid1 sda1[0] sdb1[1] > iteration 3 > State : clean > clean > md0 : active raid1 sda1[0] sdb1[1] > iteration 4 > State : clean > clean > md0 : active raid1 sda1[0] sdb1[1] > iteration 5 > State : clean > clean > md0 : active raid1 sda1[0] sdb1[1] >=20 > so, mdadm --detail & array_state shows array is "clean", while > /proc/mdstat shows array is "active" (no reads/writes happen). >=20 > Some value is lieing or being misunderdstanded by me... In mdstat you have 'active' or 'inactive'. You cannot access an array = at all until it is active. If you are assembling an array bit by bit with "md= adm -I", it will be inactive until all the devices appear. Then it will be active. In mdadm "State :" you have 'active' or 'clean'. as described above. I= t used to be 'dirty' or 'clean' but people were confused by having 'dirty' arr= ays in normal operation. So I changed it to 'active' and now it confuses a different set of people. You just can't win can you :-) NeilBrown >=20 > > > > > > > >> > >> cheers, > >> =A0 harald > >> > >> well, I have only 2 hard drives and no space for more.. > >> > >> Am 16.08.2011 03:29, schrieb Roberto Spadim: > >> > try raid10 far layout > >> > > >> > 2011/8/15 Harald Nikolisin >> > > > >> > > >> > =A0 =A0 Since a long time I'm unhappy with the performance of my= RAID-1 system. > >> > =A0 =A0 Investigation with atop and iostat unveils that the disk= utilization is > >> > =A0 =A0 always on a certain level although nothing happens on th= e system. In the > >> > =A0 =A0 case of reading or writing files the utilization boosts = always to 100% > >> > =A0 =A0 for a long time. Very ugly examples are "Firefox startin= g" or "zypper > >> > =A0 =A0 updates". > >> > =A0 =A0 That is snapshot of the output of iostat: > >> > > >> > > >> > =A0 =A0 Device: =A0 =A0 =A0 =A0 rrqm/s =A0 wrqm/s =A0 =A0 r/s =A0= =A0 w/s =A0 rsec/s =A0 wsec/s > >> > =A0 =A0 avgrq-sz avgqu-sz =A0 await =A0svctm =A0%util > >> > =A0 =A0 sda =A0 =A0 =A0 =A0 =A0 =A0 =A0 0,00 =A0 =A0 0,00 =A0 =A0= 0,00 =A0 =A07,33 =A0 =A0 0,00 =A0 =A043,33 > >> > =A0 =A0 5,91 =A0 =A0 0,33 =A0 43,18 =A033,32 =A024,43 > >> > =A0 =A0 sdb =A0 =A0 =A0 =A0 =A0 =A0 =A0 0,00 =A0 =A0 0,00 =A0 =A0= 0,00 =A0 =A07,33 =A0 =A0 0,00 =A0 =A043,33 > >> > =A0 =A0 5,91 =A0 =A0 0,35 =A0 45,59 =A039,73 =A029,13 > >> > =A0 =A0 md0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 0,00 =A0 =A0 0,00 =A0 =A0= 0,00 =A0 =A00,67 =A0 =A0 0,00 =A0 =A0 5,33 > >> > =A0 =A0 8,00 =A0 =A0 0,00 =A0 =A00,00 =A0 0,00 =A0 0,00 > >> > =A0 =A0 md1 =A0 =A0 =A0 =A0 =A0 =A0 =A0 0,00 =A0 =A0 0,00 =A0 =A0= 0,00 =A0 =A00,33 =A0 =A0 0,00 =A0 =A0 5,33 > >> > =A0 =A0 16,00 =A0 =A0 0,00 =A0 =A00,00 =A0 0,00 =A0 0,00 > >> > =A0 =A0 md2 =A0 =A0 =A0 =A0 =A0 =A0 =A0 0,00 =A0 =A0 0,00 =A0 =A0= 0,00 =A0 =A00,33 =A0 =A0 0,00 =A0 =A0 1,00 > >> > =A0 =A0 3,00 =A0 =A0 0,00 =A0 =A00,00 =A0 0,00 =A0 0,00 > >> > =A0 =A0 md3 =A0 =A0 =A0 =A0 =A0 =A0 =A0 0,00 =A0 =A0 0,00 =A0 =A0= 0,00 =A0 =A00,00 =A0 =A0 0,00 =A0 =A0 0,00 > >> > =A0 =A0 0,00 =A0 =A0 0,00 =A0 =A00,00 =A0 0,00 =A0 0,00 > >> > =A0 =A0 md4 =A0 =A0 =A0 =A0 =A0 =A0 =A0 0,00 =A0 =A0 0,00 =A0 =A0= 0,00 =A0 =A00,00 =A0 =A0 0,00 =A0 =A0 0,00 > >> > =A0 =A0 0,00 =A0 =A0 0,00 =A0 =A00,00 =A0 0,00 =A0 0,00 > >> > =A0 =A0 md5 =A0 =A0 =A0 =A0 =A0 =A0 =A0 0,00 =A0 =A0 0,00 =A0 =A0= 0,00 =A0 =A00,33 =A0 =A0 0,00 =A0 =A0 0,67 > >> > =A0 =A0 2,00 =A0 =A0 0,00 =A0 =A00,00 =A0 0,00 =A0 0,00 > >> > > >> > =A0 =A0 I checked with mdadm if a resync happens or so, but this= is not the > >> > =A0 =A0 case. The state says "active" on all RAID devices - btw.= what is the > >> > =A0 =A0 difference to "clean" ? > >> > > >> > =A0 =A0 thanks for any hints, > >> > =A0 =A0 =A0harald > >> > =A0 =A0 -- > >> > =A0 =A0 To unsubscribe from this list: send the line "unsubscrib= e linux-raid" in > >> > =A0 =A0 the body of a message to majordomo@vger.kernel.org > >> > =A0 =A0 > >> > =A0 =A0 More majordomo info at =A0http://vger.kernel.org/majordo= mo-info.html > >> > > >> > > >> > > >> > > >> > -- > >> > Roberto Spadim > >> > Spadim Technology / SPAEmpresarial > >> > >> > >> -- > >> To unsubscribe from this list: send the line "unsubscribe linux-ra= id" in > >> the body of a message to majordomo@vger.kernel.org > >> More majordomo info at =A0http://vger.kernel.org/majordomo-info.ht= ml > > > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-rai= d" in > > the body of a message to majordomo@vger.kernel.org > > More majordomo info at =A0http://vger.kernel.org/majordomo-info.htm= l > > >=20 >=20 >=20 -- 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