[Bug 1045052] [NEW] slow boot (exe=fsck) with root partition on md

[LeForgeron]

Public bug reported:

Hello,

This was initialy asked as a question, which get answered with a
suggestion to report a bug.


My system is currently slow to boot (bootchart reports about 70s in exe,
between mdadm+udevadm and udev+udevadm : e.g. from start of record, 5.5s
to reach end of modprobe, then small wait-for-root, mdadm & udevadm at
6.2s, then exe till 73.1s, then continue booting normally
(udev,udevadm,hostname, plymouthd, ureadahead... everything goes in
before at 85s)

My root partition(/) is a raid5 on 7 disks, on md0, using ext4fs. (no
LVM; no internal partition table)

Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
md0 : active raid5 sdb1[1] sdc1[2] sda1[0] sde1[4] sdf1[5] sdg1[6] sdd1[3]
      11721077760 blocks super 1.2 level 5, 512k chunk, algorithm 2 [7/7] [UUUUUUU]
      bitmap: 2/15 pages [8KB], 65536KB chunk

unused devices: <none>

>From a blog on the web ( http://georgovassilis.blogspot.fr/2011/12/exe-
process-on-slow-ubuntu-bootchart.html ), it seems due to a failure to
stop cleanly the ext4fs on shutdown/reboot.

Am I right to think that in my situation, the mdadm should not be stopped before the umountfs or umountroot is performed ?
(/etc/rc0.d (and rc6.d) lists K25mdadm, S40umountfs and S60umountroot )
Is it safe to remove K25mdadm from runlevel 0 & 6 ?


package mdadm  : 3.2.5-1ubuntu0.2

Description:    Ubuntu 12.04.1 LTS
Release:        12.04

mdadm:
  Installed: 3.2.5-1ubuntu0.2
  Candidate: 3.2.5-1ubuntu0.2
  Version table:
 *** 3.2.5-1ubuntu0.2 0
        500 http://archive.ubuntu.com/ubuntu/ precise-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     3.2.3-2ubuntu1 0
        500 http://archive.ubuntu.com/ubuntu/ precise/main amd64 Packages


I would expect the system to boot in less than 50 seconds, and especially, without a 1 minute of no screen display but a single flashing "_" (was grub found ? is the bios still checking... plymouth shows up only after the expiration of that 60+ seconds black screen, so if I do turn the head from the screen at boot time, I cannot know)

What happen instead: bios runs, grub runs then disappear and after a
very short disk activity (led), nothing seems to happens for at least
60s (I guess it's all in memory-cached i/o past the few seconds).

** Affects: mdadm (Ubuntu)
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1045052

Title:
  slow boot (exe=fsck) with root partition on md

Status in “mdadm” package in Ubuntu:
  New

Bug description:
  Hello,

  This was initialy asked as a question, which get answered with a
  suggestion to report a bug.


  My system is currently slow to boot (bootchart reports about 70s in
  exe, between mdadm+udevadm and udev+udevadm : e.g. from start of
  record, 5.5s to reach end of modprobe, then small wait-for-root, mdadm
  & udevadm at 6.2s, then exe till 73.1s, then continue booting normally
  (udev,udevadm,hostname, plymouthd, ureadahead... everything goes in
  before at 85s)

  My root partition(/) is a raid5 on 7 disks, on md0, using ext4fs. (no
  LVM; no internal partition table)

  Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
  md0 : active raid5 sdb1[1] sdc1[2] sda1[0] sde1[4] sdf1[5] sdg1[6] sdd1[3]
        11721077760 blocks super 1.2 level 5, 512k chunk, algorithm 2 [7/7] [UUUUUUU]
        bitmap: 2/15 pages [8KB], 65536KB chunk

  unused devices: <none>

  From a blog on the web ( http://georgovassilis.blogspot.fr/2011/12
  /exe-process-on-slow-ubuntu-bootchart.html ), it seems due to a
  failure to stop cleanly the ext4fs on shutdown/reboot.

  Am I right to think that in my situation, the mdadm should not be stopped before the umountfs or umountroot is performed ?
  (/etc/rc0.d (and rc6.d) lists K25mdadm, S40umountfs and S60umountroot )
  Is it safe to remove K25mdadm from runlevel 0 & 6 ?

  
  package mdadm  : 3.2.5-1ubuntu0.2

  Description:    Ubuntu 12.04.1 LTS
  Release:        12.04

  mdadm:
    Installed: 3.2.5-1ubuntu0.2
    Candidate: 3.2.5-1ubuntu0.2
    Version table:
   *** 3.2.5-1ubuntu0.2 0
          500 http://archive.ubuntu.com/ubuntu/ precise-updates/main amd64 Packages
          100 /var/lib/dpkg/status
       3.2.3-2ubuntu1 0
          500 http://archive.ubuntu.com/ubuntu/ precise/main amd64 Packages

  
  I would expect the system to boot in less than 50 seconds, and especially, without a 1 minute of no screen display but a single flashing "_" (was grub found ? is the bios still checking... plymouth shows up only after the expiration of that 60+ seconds black screen, so if I do turn the head from the screen at boot time, I cannot know)

  What happen instead: bios runs, grub runs then disappear and after a
  very short disk activity (led), nothing seems to happens for at least
  60s (I guess it's all in memory-cached i/o past the few seconds).

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