>>>>> "Neil" == Neil Brown <neilb@xxxxxxx> writes:
Neil> On Wed, 14 Jul 2010 12:53:45 +0200
Neil> Tomasz Chmielewski <mangoo@xxxxxxxx> wrote:
>> I'm trying to create RAID-1 with external bitmap with this command:
>>
>> mdadm --create /dev/md11 --level=1 --bitmap=/mnt/src/bitmap --raid-devices 2 /dev/storage/origin missing
>>
>>
>> /dev/storage/origin is 1.2 TB; is placed on "stacked" block devices like this:
>>
>> RAID-5 -> dm-crypt -> LVM-2 -> /dev/storage/origin
>>
>>
>> /mnt/src/bitmap is technically the same stacked device, except the last LVM volume:
>>
>> RAID-5 -> dm-crypt -> LVM-2 -> /dev/storage/src -> /mnt/src/bitmap
>>
>> (although I tried to keep bitmap outside of this RAID-5 device, and it was still hanging).
>>
>>
>> When started with "strace", mdadm hangs with 100% CPU usage after opening /mnt/src/bitmap:
>>
>> (...)
>> rename("/var/run/map.new", "/var/run/map") = 0
>> flock(3, LOCK_UN) = 0
>> close(3) = 0
>> munmap(0x6ff40000, 4096) = 0
>> unlink("/var/run/map.lock") = 0
>> ioctl(4, 0x800c0910, 0x77f5f89c) = 0
>> fstat64(4, {st_mode=S_IFBLK|0600, st_rdev=makedev(9, 1), ...}) = 0
>> fstat64(4, {st_mode=S_IFBLK|0600, st_rdev=makedev(9, 1), ...}) = 0
>> ioctl(4, 0x800c0910, 0x77f5f7cc) = 0
>> ioctl(4, 0x40480923, 0x77f5f854) = 0
>> access("/mnt/src/bitmap", F_OK) = -1 ENOENT (No such file or directory)
>> open("/mnt/src/bitmap", O_WRONLY|O_CREAT|O_TRUNC|O_LARGEFILE, 0666) = 3
>>
>>
Neil> Hmm... that's rather embarrassing.
Neil> This patch should fit it. Or you can explicitly set a bitmap chunk size -
Neil> aim for several megabyte.
Neil> diff --git a/bitmap.c b/bitmap.c
Neil> index beef2dc..44a8677 100644
Neil> --- a/bitmap.c
Neil> +++ b/bitmap.c
Neil> @@ -373,7 +373,7 @@ int CreateBitmap(char *filename, int force, char uuid[16],
Neil> */
Neil> chunksize = DEFAULT_BITMAP_CHUNK;
Neil> /* <<20 for 2^20 chunks, >>9 to convert bytes to sectors */
Neil> - while (array_size > (chunksize << (20-9)))
Neil> + while (array_size > ((unsigned long long)chunksize << (20-9)))
Neil> chunksize <<= 1;
Neil> }
How about also replacing the magic numbers 20 and 9 with usefully
named constants as well? I realize the comment tells you what's
going on here, but I just boggle a bit when I see 20-9 in the source.
:-)
John
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