From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: Re: Spin down Date: Tue, 6 Dec 2011 15:39:23 +1100 Message-ID: <20111206153923.203df175@notabene.brown> References: <20111205171115.044b1705@notabene.brown> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=PGP-SHA1; boundary="Sig_/I2Ad1EATPscEuHxfn90QJFY"; protocol="application/pgp-signature" Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Vincent Pelletier Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids --Sig_/I2Ad1EATPscEuHxfn90QJFY Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On Mon, 5 Dec 2011 08:49:03 +0100 Vincent Pelletier wrote: > On Mon, Dec 5, 2011 at 7:11 AM, NeilBrown wrote: > > 5 seconds suggests a bitmap update. =A0Do you have an internal bitmap? >=20 > I don't, but I enabled it on those arrays before with default delay. > I then removed it when I suspected (with help of block_dump) it to > cause spin-ups, and I noticed an improvement. Recently, the machine > was restarted (once on 3.0 kernel, and again to update to 3.1), and > after both restarts those 5s periodic writes occurred. >=20 > > Then try adding it back with a longer delay > > =A0mdadm --grow /dev/md0 --bitmap=3Dinternal --delay=3D60 >=20 > Adding bitmaps on both arrays (md0 and md1), 5s periodic writes disappear. > Removing bitmaps seems to preserve the improvement. >=20 > Could the delay setting have survived on-disk and be used when > initializing the array, but cleared when mdadm later disables bitmap > usage ? >=20 > > What kernel version are you running? >=20 > 3.1.4, according to dpkg: > ii linux-image-3.1.0-1-amd64 3.1.4-1 > Linux 3.1 for 64-bit PCs >=20 > Regards, Hmm... I cannot reproduce this which makes it harder. Can you enable dynamic debugging on md? Make sure CONFIG_DYNAMIC_DEBUG is set, mount debugfs on /sys/kernel/debug a= nd echo module md_mod +p > /sys/kernel/debug/dynamic_debug/control then look for extra messages in the kernel logs, starting "md:" most likely. You'll almost certainly see something like [ 1851.559629] md: waking up MD thread md0_raid1. [ 1851.625819] md: updating md0 RAID superblock on device (in sync 1) [ 1851.656878] md: (write) sdb's sb offset: 8 [ 1851.656915] md: (write) sda's sb offset: 8 every 5 seconds. If you could confirm that and report if there is anything else reported that might help. NeilBrown --Sig_/I2Ad1EATPscEuHxfn90QJFY Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.18 (GNU/Linux) iQIVAwUBTt2chTnsnt1WYoG5AQJu1w//R9eX/VHvp2JzhMRV022qAUsnuW6R+Nh1 gICn6WDLuy7OG/Yf8L9405PQ7+yEYGzELBWPY3Dbz2nvQEz8tNFWO5vQxKwHlLik ikU63vozdnlGtlXuzV2WV2JlQ+U9AYMUrw+Ie25gxCQx8ZHhJJusjKEZpiXCs+2v gLC7huwVoc0Ld0lAqQPkeMgD2DRb1baiYN/AixAkASDO+ep9FYTG9mmUY1FZPS4K v+2QQtY7OFXYiRPOpmeqODONTrYjC4E0wC5Z4VonEADCvPeR3988xR+JHMMu/911 tBpZBZWlAlkGeUX4asEpuDd9gMQG4iwBH3fJtgPLbSQr8VyKV0HzO3B089wApyxp x9sOgXC22Y5Z9CbIUwgChX4DhtAF9jdbZIjm9a43jMiHnCmTU+ZB2rUnbkGKhH7S JyfU8WHYWLYE/AGgZuHlfadXBeL5N8W1Aq1Yj02n/jZO9YZqUl9dS+hpWEeu0e8v QM2Kq3sZYOeOSN6HIaGuIeVAR+Elt28Shr6yt9H33xVCNKzlhJwXGoAkDNVs2Pml 2eR+ZD5w90xiE+AH931V0yhSHtdXI1O4G97MKuT1o99iUekny0scd3l6h69AJiWc shNLK4O8WHnNh1Ob0wagEOU1nfg8WqPpgUBelP0ERJXs82iLV0JgGMqHbFuCBLuJ eFPg2G27Oao= =5MW8 -----END PGP SIGNATURE----- --Sig_/I2Ad1EATPscEuHxfn90QJFY--