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kenyeeOffline
15 Post subject: (solved) mdraid not starting up w/ 3.8.0-1 kernel?  PostPosted: 20.02.2013, 00:00



Joined: 2010-09-29
Posts: 85

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I tried installing the latest 3.8.0-1 kernel and my mdraid drives never started up. 3.7 works fine though.

Anyone hit this problem?

My /etc/initramfs-tools/modules doesn't have anything in it, but 3.7 seems to have no problems spinning up the RAID1 mdraid.
I'm thinking I can add md_mod and raid1 into this file, but I'm not sure if that's a workaround for another issue I should be fixing instead...
 
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slhOffline
Post subject: RE: mdraid not starting up w/ 3.8.0-1 kernel?  PostPosted: 20.02.2013, 00:50



Joined: 2010-08-25
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Try to add "rootdelay=1" as kernel parameter, e.g.:
      Code:
GRUB_CMDLINE_LINUX="rootdelay=1"
in /etc/default/grub and run update-grub afterwards. You can also add this setting on the fly, using the grub menu for the current boot. You might have to increase that value, although 1 seconds seems to be sufficient.

There appears to be a latent race condition regarding devmapper and initramfs-tools (or its mdadm/ lvm2 scripts) on some systems (which CPU and mainboard chipset?). This was already a problem with kernel 3.5 for a particular hardware type, which mostly disappeared with 3.6 and 3.7 - now with 3.8 it might be back and affect a wider range of hardware. I've already spent quite a lot of time debugging this, both with 3.5 and now with 3.8~ pre-releases, but the race condition is very hard to bisect, due to false negatives voiding the results and the issue only showing on a distinct subset of hardware.

To be clear about the situation, this race condition is a problem in the initramfs (initramfs-tools or devmapper/mdadm/lvm2 hooks), which isn't event based, but rather expects the devices to show up in time (although rootwait does not work). Depending on slight timing variation betweens different (upstream-) kernel versions, this might -or might not- trigger 'semi-randomly'. What makes this issue hard to catch, is that it doesn't fail reliably all the time - the very same kernel can fail almost all the time, but 'magically' work 5 times in a row while debugging…
A discussion about very similar issues in Debian can be found here, #688711. Despite that bug being marked as closed now, I'm pretty confident that it just disappeared 'by chance', due to minimal timing changes between the tested kernel versions.

I'm very interested if setting a rootdelay value can work around your problem with kernel 3.8 - and also which hardware you're dealing with.
 
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tuxmanOffline
Post subject: RE: mdraid not starting up w/ 3.8.0-1 kernel?  PostPosted: 20.02.2013, 10:38



Joined: 2010-09-11
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Thanks slh !,
it seems that " GRUB_CMDLINE_LINUX="rootdelay=1" " helped here solving it.
I had same problem here with kernel 3.8, mdadm was very rarely able to start, but mostly it doesn't find the devices,
with kernel 3.7 all went OK before .
Here some information about my system:
( inxi -v2 )
System: Host: tux Kernel: 3.8-0.towo-siduction-amd64 x86_64 (64 bit)
Desktop: KDE 4.9.5 Distro: siduction 11.1 One Step Beyond - kde - (201112302141)
Machine: Mobo: Gigabyte model: GA-890GPA-UD3H version: x.x Bios: Award version: FF date: 03/07/2011
CPU: Quad core AMD Phenom II X4 945 (-MCP-) clocked at 800.00 MHz
Graphics: Card: Advanced Micro Devices [AMD] nee ATI Juniper [Radeon HD 5700 Series]
X.Org: 1.12.4 drivers: ati,radeon Resolution: 1280x1024@60.0hz
GLX Renderer: Gallium 0.4 on AMD JUNIPER GLX Version: 2.1 Mesa 8.0.5
Network: Card: Realtek RTL8111/8168B PCI Express Gigabit Ethernet controller driver: r8169
Drives: HDD Total Size: 4500.9GB (15.0% used) 1: model: Hitachi_HDS72302
2: model: SAMSUNG_HD501LJ 3: model: Hitachi_HDS72101 4: model: Hitachi_HDS72101
RAID: Devices: 1: /dev/md1 2: /dev/md0
Info: Processes: 182 Uptime: 11 min Memory: 608.5/7989.1MB Client: Shell (bash) inxi: 1.8.37

Sorry, I know my english is bad.

tuxman
 
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kenyeeOffline
Post subject: RE: mdraid not starting up w/ 3.8.0-1 kernel?  PostPosted: 22.02.2013, 14:24



Joined: 2010-09-29
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Thanks, slh. Adding the delay worked fine for me. It was pretty solid before (always happened w/ 3.8 but never w/ previous kernels). I left the delay in the grub script so hopefully, the workaround will be permanent Smile
I do have LVM on top of mdraid, but my issue was the mdraid drives weren't coming on line before LVM started so it choked.

Thanks tuxman for that inxi command...I didn't know it existed but it's a pretty useful tool. Here's my setup:

System: Host: JumpGate Kernel: 3.8-0.slh.1-aptosid-amd64 x86_64 (64 bit) Desktop: KDE 4.8.4 Distro: sidux64-20070310-d:1
Machine: Mobo: ASUSTeK model: M3A78-EM version: Rev X.0x Bios: American Megatrends version: 0404 date: 06/03/2008
CPU: Dual core AMD Athlon 4850e (-MCP-) clocked at 1000.00 MHz
Graphics: Card: Advanced Micro Devices [AMD] nee ATI RS780 [Radeon HD 3200]
X.Org: 1.12.4 drivers: ati,radeon (unloaded: fbdev,vesa) Resolution: 1920x1200@60.0hz
GLX Renderer: Gallium 0.4 on AMD RS780 GLX Version: 2.1 Mesa 8.0.5
Network: Card-1: Intel 82557/8/9/0/1 Ethernet Pro 100 driver: e100
Card-2: Realtek RTL8111/8168B PCI Express Gigabit Ethernet controller driver: r8169
Drives: HDD Total Size: 5001.0GB (1.3% used) 1: model: WDC_WD20EFRX
2: model: SAMSUNG_HD204UI 3: model: WDC_WD1001FALS
RAID: Devices: 1: /dev/md1 2: /dev/md0
Info: Processes: 210 Uptime: 12 min Memory: 1344.9/3708.2MB Client: Shell (bash) inxi: 1.8.38

Our systems look fairly old by today's standards, so that's probably why this race condition is more consistent for us...
 
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