[dm-devel] Re: [RFC] [PATCH] lvm2: mirroredlog support

[malahal at us.ibm.com]

Thank you Takahiro for your comments. They all need to be fixed! I also
found that 'lvremove' doesn't remove the device mapper tables for the
"log mirror".

--Malahal.

Takahiro Yasui [tyasui at redhat.com] wrote:
> malahal at us.ibm.com wrote:
> > This patch adds '--mirroredlog' option to LVM commands to create a
> > mirror with mirrored log device. Rebased to the latest LVM code
> > (LVM2.2.02.43). Appreciate any comments.
> 
> Hi, Malahal
> 
> This is the additional test results of mirrored log. Currently your
> patch is proposed by "RFC", and these might be known issues to you,
> but I hope this reports would be helpful to improve your patch.
> Any comments are welcome.
> 
> 
> 0. Test environment
>   - LVM2.2.02.43 with mirrored log patch
>   - vg00 is composed of 8 PVs (/dev/sd[c-j])
> 
> 
> 1. SIGSEGV at converting a core log to a mirrored log
> 
>   # dmsetup status
>   vg00-lv00_mimage_1: 0 24576 linear
>   vg00-lv00_mimage_0: 0 24576 linear
>   vg00-lv00: 0 24576 mirror 2 253:3 253:4 24/24 1 AA 1 core
> 
>   # lvconvert -m1 --mirroredlog /dev/vg00/lv00
>   Segmentation fault
> 
>   # lvconvert -m2 --mirroredlog /dev/vg00/lv00
>   Segmentation fault
> 
> 
> 2. Fail at conversion from 2 legs to 3 legs
> 
>   lv00 in vg00 has 2 legs (2 log legs and 2 data legs), and when it is
>   converted to the structure with 3 lets, the conversion fails.
> 
>   vg00-lv00 (253:5)
>    + vg00-lv00_mimage_1 (253:4)
>    + vg00-lv00_mimage_0 (253:3)
>    + vg00-lv00_mlog (253:2)
>       + vg00-lv00_mlog_mimage_1 (253:1)
>       + vg00-lv00_mlog_mimage_0 (253:0)
> 
>   # lvconvert -m2 --mirroredlog /dev/vg00/lv00
>     device-mapper: reload ioctl failed: No such device or address
>     Failed to lock lv00
>   # dmsetup status
>   vg00-lv00_mimage_2: 0 8192 linear    <-- data leg is created
>   vg00-lv00_mimage_1: 0 24576 linear
>   vg00-lv00_mlog_mimage_1: 0 8192 linear
>   vg00-lv00_mimage_0: 0 24576 linear
>   vg00-lv00_mlog_mimage_0: 0 8192 linear
>   vg00-lv00_mimagetmp_2: 0 24576 error <-- temporary data log exists
>   vg00-lv00_mlog: 0 8192 mirror 2 253:1 253:2 8/8 1 AA 1 core
>   vg00-lv00: 0 24576 mirror 2 253:4 253:5 24/24 1 AA 3 disk 253:3 A
> 
> 
> 3. Fail at conversion from disk log to mirrored log
> 
>   # dmsetup status
>   vg00-lv00_mimage_1: 0 24576 linear
>   vg00-lv00_mimage_0: 0 24576 linear
>   vg00-lv00_mlog: 0 8192 linear
>   vg00-lv00: 0 24576 mirror 2 253:1 253:2 24/24 1 AA 3 disk 253:0 A
> 
>   # lvconvert -m1 --mirroredlog /dev/vg00/lv00
>   Logical volume lv00 already has 1 mirror(s).
> 
>    => disk log should be converted to mirrored log?
> 
>   # lvconvert -m2 --mirroredlog /dev/vg00/lv00
>   device-mapper: reload ioctl failed: No such device or address
>   Failed to lock lv00
>   # dmsetup status
>   vg00-lv00_mimage_2: 0 8192 linear
>   vg00-lv00_mimage_1: 0 24576 linear
>   vg00-lv00_mimage_0: 0 24576 linear
>   vg00-lv00_mimagetmp_2: 0 24576 error
>   vg00-lv00_mlog: 0 8192 linear
>   vg00-lv00: 0 24576 mirror 2 253:1 253:2 24/24 1 AA 3 disk 253:0 A
> 
>    => disk log should be converted to mirrored log with 3 legs?
> 
> 
> Thanks,
> ---
> Takahiro Yasui
> Hitachi Computer Products (America), Inc.
>