From mboxrd@z Thu Jan 1 00:00:00 1970 From: "P. Gautschi" Subject: Re: --no-degraded does not work Date: Mon, 10 Nov 2014 04:13:00 +0100 Message-ID: <54602D3C.2070005@gautschi.net> References: <545CF69B.6040307@gautschi.net> <20141108102247.687b8863@notabene.brown> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20141108102247.687b8863@notabene.brown> Sender: linux-raid-owner@vger.kernel.org To: NeilBrown Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids > Do you have a particular goal, or were you just making sure you understood? Both. My goal is to keep my data a safe as possible in case of a 2 and more disk failure for non permanent failures. During experiments I has problems with a power cable and I was not able to recover from this situation. (3 Disk ok, 2 that failed after each other) I therefor would not like to start the array when not all disk are ok. I created a script that checks in readonly mode first. On 2014-11-08 00:22, NeilBrown wrote: > On Fri, 07 Nov 2014 17:43:07 +0100 "P. Gautschi" > wrote: > >> As far as I understand the documentation --assemble --no-degraded should not start a degraded array. >> However on my system (kubuntu 14.10) >> >> # mdadm --assemble --no-degraded /dev/md0 /dev/sdb1 /dev/sdc1 /dev/sdd1 /dev/sde1 /dev/sdf1 >> mdadm: /dev/md0 has been started with 4 drives (out of 5). >> >> # mdadm --detail /dev/md0 >> /dev/md0: >> Version : 1.2 >> Creation Time : Tue Nov 4 15:26:46 2014 >> Raid Level : raid5 >> Array Size : 599469328 (571.70 GiB 613.86 GB) >> Used Dev Size : 149867332 (142.92 GiB 153.46 GB) >> Raid Devices : 5 >> Total Devices : 4 >> Persistence : Superblock is persistent >> >> Intent Bitmap : Internal >> >> Update Time : Fri Nov 7 17:22:53 2014 >> State : clean, degraded >> Active Devices : 4 >> Working Devices : 4 >> Failed Devices : 0 >> Spare Devices : 0 >> >> Layout : left-symmetric >> Chunk Size : 4K >> >> Name : 0 >> UUID : c7465b19:c149b2d1:5b4d88ce:8c6ce432 >> Events : 642 >> >> Number Major Minor RaidDevice State >> 0 0 0 0 removed >> 1 8 33 1 active sync /dev/sdc1 >> 2 8 49 2 active sync /dev/sdd1 >> 3 8 65 3 active sync /dev/sde1 >> 5 8 81 4 active sync /dev/sdf1 >> >> the array IS started when removing one disk, stopping it, reconnecting the disk and then assemble the array. >> Is this the supposed behavior? > > Yes, that is the correct behaviour, though I admit that it is slightly > unintuitive. > > --no-degraded will cause mdadm to refuse to assemble an array which is more > degraded than it was last time it was active. > > So if you have an optimal array, stop it, then try to assemble with some > devices missing, then --no-degraded will cause that to fail. > > If the array is already degraded, then there doesn't seem much point in > stopping it from assembling. > > Do you have a particular goal, or were you just making sure you understood? > > Thanks, > NeilBrown