Re: RAID10-reshape crashed due to memory allocation problem

[NeilBrown <neilb@suse.de>]

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On Thu, 7 Aug 2014 23:06:46 +0200 mdraid.pkoch@dfgh.net (Peter Koch) wrote:

> Dear readers,
> 
> seems like memory is leaking when a RAID10-array is reshaped.

Only in Linux 3.14.
You need commit cc13b1d1500656a20e41960668f3392dda9fa6e2
which is in v3.14.16

So even though you didn't tell me what kernel version you were using, I
knew:-)

(always report mdadm version and kernel version).

NeilBrown


> 
> Here are the details of what I did:
> 
> RAID10-array consisting of 13 disks (2TB each) and one spare was
> grown into a 16 disk RAID10-array by adding two more spares and
> then doing  mdadm --grow /dev/md5 --raid-devices=16
> 
> When the reshape operation reached 80% (after 20 hours) the system
> became unresponsive and crashed soon after. Console output showed
> something like "... could not allocate memory block ..."
> 
> The machine has 32GB of RAM.
> 
> After the machine was rebooted the reshape operation was running
> for 6 more hours and was followed by an 8 hour resync.
> 
> Everything seems to be OK now, but according to /proc/meminfo
> only 15GB of RAM are available. Much too low for a system that
> is almost idle.
> 
> I will reboot the machine at our next maintenance window and
> compare its available memory with the situation right now.
> 
> Is restarting the reshape operation after a crash really safe?
> Should I check the correctness of my array somehow?
> 
> Kind regards
> 
> Peter Koch
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