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SubjectRe: What happened with the Patch "New RAID library supporting up to six parities"
On Tue, 21 Oct 2014 13:16:52 +0000 Ronny Egner
<ronnyegner@ronnyegner-consulting.de> wrote:

> Hi Neil,
>
>
> i did a short test and it works so far. Here are my results. Let me know
> if you need something more:
>
> (TL;DR: Wonderful patch. Tested with PAR6 (= six parities) and was able to
> recover from losing five disks at once.)

Thanks for doing this - it does sound like they are useful.

As you note, the patches only include support for btrfs, not for md/raid.

I can carry the lib/raid stuff as I am nominally responsible for that, but I
cannot send it upstream until there is a user ready to use it. If the btrfs
team can be convinced to include the functionality: good. If not, there is
nothing I can do to help.

There would be a non-trivial amount of effort to integrate this support into
md/raid. I am not free to do that at present but if someone else wants to put
in the time and effort, I can certainly provide guidance and review.

(and please don't send emails about md/raid to me personally. Always include
the list at least in 'cc').

Thanks,
NeilBrown


>
>
>
> The patches apply against 3.14.22 and btrfs-progs 3.12 but not against the
> recent 3.18-rc1 and btrfs-progs > 3.12.
>
>
> root@ubuntu-1204-build:~# btrfs --version
> Btrfs v3.12-dirty
>
> root@ubuntu-1204-build:~# uname -a
> Linux ubuntu-1204-build 3.14.22 #3 SMP Tue Oct 21 13:00:08 CEST 2014
> x86_64 x86_64 x86_64 GNU/Linux
>
>
> For the tests i used a VM with 4 GB memory, two cores and 15 disks with
> 150 GB each. Every disk looked like this:
>
> root@ubuntu-1204-build:~# fdisk /dev/sdi
>
> Command (m for help): p
>
> Disk /dev/sdi: 157.3 GB, 157286400000 bytes
> 81 heads, 30 sectors/track, 126419 cylinders, total 307200000 sectors
> Units = sectors of 1 * 512 = 512 bytes
> Sector size (logical/physical): 512 bytes / 512 bytes
> I/O size (minimum/optimal): 512 bytes / 512 bytes
> Disk identifier: 0x5b5d7269
>
> Device Boot Start End Blocks Id System
> /dev/sdi1 2048 307199999 153598976 83 Linux
>
>
> File system created:
>
> root@ubuntu-1204-build:~# mkfs.btrfs -dpar6 -L testpar6 /dev/sdh1
> /dev/sdi1 /dev/sdj1 /dev/sdk1 \
> /dev/sdl1 /dev/sdm1 /dev/sdn1 /dev/sdo1 /dev/sdp1
> /dev/sdq1 /dev/sdr1 \
> /dev/sds1 /dev/sdt1 /dev/sdu1 /dev/sdv1
>
>
> Turning ON incompat feature 'extref': increased hardlink limit per file
> to 65536
> Turning ON incompat feature 'par3456': raid support with up to six
> parities
> adding device /dev/sdi1 id 2
> adding device /dev/sdj1 id 3
> adding device /dev/sdk1 id 4
> adding device /dev/sdl1 id 5
> adding device /dev/sdm1 id 6
> adding device /dev/sdn1 id 7
> adding device /dev/sdo1 id 8
> adding device /dev/sdp1 id 9
> adding device /dev/sdq1 id 10
> adding device /dev/sdr1 id 11
> adding device /dev/sds1 id 12
> adding device /dev/sdt1 id 13
> adding device /dev/sdu1 id 14
> adding device /dev/sdv1 id 15
> fs created label testpar6 on /dev/sdh1
> nodesize 16384 leafsize 16384 sectorsize 4096 size 2.15TiB
> Btrfs v3.12-dirty
>
>
> Mount:
>
>
> root@ubuntu-1204-build:~# mount /dev/sdh1 /mnt
>
> Stats:
>
> root@ubuntu-1204-build:~# df -h
> Filesystem Size Used Avail Use% Mounted on
> /dev/mapper/vgroot-lvroot 26G 17G 8.4G 67% /
> none 4.0K 0 4.0K 0% /sys/fs/cgroup
> udev 1.6G 4.0K 1.6G 1% /dev
> tmpfs 331M 1.1M 330M 1% /run
> none 5.0M 0 5.0M 0% /run/lock
> none 1.7G 0 1.7G 0% /run/shm
> none 100M 0 100M 0% /run/user
> /dev/sdh1 2.2T 2.8M 2.2T 1% /mnt
>
>
> Data, single: total=8.00MiB, used=0.00
> Data, PAR6: total=9.00GiB, used=995.16MiB
> System, RAID1: total=8.00MiB, used=16.00KiB
> System, single: total=4.00MiB, used=0.00
> Metadata, RAID1: total=1.00GiB, used=65.59MiB
> Metadata, single: total=8.00MiB, used=0.00
>
> root@ubuntu-1204-build:/mnt# btrfs fi show
> Label: testpar6 uuid: 79d3c5e4-74ce-4464-a509-ef666dcd9073
> Total devices 15 FS bytes used 1.04GiB
> devid 1 size 146.48GiB used 1.02GiB path /dev/sdh1
> devid 2 size 146.48GiB used 1.00GiB path /dev/sdi1
> devid 3 size 146.48GiB used 1.00GiB path /dev/sdj1
> devid 4 size 146.48GiB used 1.00GiB path /dev/sdk1
> devid 5 size 146.48GiB used 1.00GiB path /dev/sdl1
> devid 6 size 146.48GiB used 1.00GiB path /dev/sdm1
> devid 7 size 146.48GiB used 1.00GiB path /dev/sdn1
> devid 8 size 146.48GiB used 1.00GiB path /dev/sdo1
> devid 9 size 146.48GiB used 1.00GiB path /dev/sdp1
> devid 10 size 146.48GiB used 1.00GiB path /dev/sdq1
> devid 11 size 146.48GiB used 1.00GiB path /dev/sdr1
> devid 12 size 146.48GiB used 2.00GiB path /dev/sds1
> devid 13 size 146.48GiB used 2.00GiB path /dev/sdt1
> devid 14 size 146.48GiB used 1.01GiB path /dev/sdu1
> devid 15 size 146.48GiB used 1.01GiB path /dev/sdv1
>
>
> Metadata and data still ‚single‘? Bug? Nevermind - lets convert it:
>
> root@ubuntu-1204-build:/mnt# btrfs balance start -mconvert=raid1 /mnt
> Done, had to relocate 4 out of 6 chunks
>
> root@ubuntu-1204-build:/mnt# btrfs fi df /mnt
> Data, single: total=8.00MiB, used=0.00
> Data, PAR6: total=9.00GiB, used=1.02GiB
> System, RAID1: total=32.00MiB, used=16.00KiB
> Metadata, RAID1: total=1.00GiB, used=67.83MiB
>
> root@ubuntu-1204-build:/mnt# btrfs balance start -dconvert=par6 /mnt
> Done, had to relocate 2 out of 4 chunks
>
> root@ubuntu-1204-build:/mnt# btrfs fi df /mnt
> Data, PAR6: total=9.00GiB, used=1.02GiB
> System, RAID1: total=32.00MiB, used=16.00KiB
> Metadata, RAID1: total=1.00GiB, used=68.72MiB
>
>
>
> OK now lets see what happens if we remove on device. Save a MD5SUM before:
>
>
> root@ubuntu-1204-build:/mnt# md5sum linux-3.14.22.tar
> 80af37cdfb2fa2239f79597c914a8c73 linux-3.14.22.tar
>
>
> (Removed one disk and replace it with a brand new, empty one)
>
>
>
>
> root@ubuntu-1204-build:~# mount /dev/sdh1 /mnt
> mount: wrong fs type, bad option, bad superblock on /dev/sdh1,
> missing codepage or helper program, or other error
> In some cases useful info is found in syslog - try
> dmesg | tail or so
>
> root@ubuntu-1204-build:~# mount /dev/sdh1 /mnt -o degraded
> root@ubuntu-1204-build:~#
>
> root@ubuntu-1204-build:~# btrfs fi show
> Label: testpar6 uuid: 79d3c5e4-74ce-4464-a509-ef666dcd9073
> Total devices 15 FS bytes used 31.42GiB
> devid 1 size 146.48GiB used 4.00GiB path /dev/sdh1
> devid 2 size 146.48GiB used 5.00GiB path /dev/sdi1
> devid 3 size 146.48GiB used 4.00GiB path /dev/sdj1
> devid 4 size 146.48GiB used 4.00GiB path /dev/sdk1
> devid 5 size 146.48GiB used 4.00GiB path /dev/sdl1
> devid 6 size 146.48GiB used 5.00GiB path /dev/sdm1
> devid 7 size 146.48GiB used 4.03GiB path /dev/sdn1
> devid 8 size 146.48GiB used 4.00GiB path /dev/sdo1
> devid 9 size 146.48GiB used 4.00GiB path /dev/sdp1
> devid 10 size 146.48GiB used 4.00GiB path /dev/sdq1
> devid 11 size 146.48GiB used 4.00GiB path /dev/sdr1
> devid 12 size 146.48GiB used 4.03GiB path /dev/sds1
> devid 13 size 146.48GiB used 4.00GiB path /dev/sdt1
> devid 14 size 146.48GiB used 4.00GiB path /dev/sdu1
> devid 15 size 146.48GiB used 4.00GiB path
>
>
> Lets replace the faulty disk:
>
> root@ubuntu-1204-build:~# btrfs device add /dev/sdv1 /mnt
> root@ubuntu-1204-build:~# btrfs device delete missing /mnt
>
> In /var/log/syslog:
>
> [ 191.442050] BTRFS warning (device sdk1): devid 15 missing
> [ 581.367659] sdv: sdv1
> [ 598.009968] BTRFS: device label testpar6 devid 16 transid 63 /dev/sdv1
> [ 614.679654] BTRFS info (device sdk1): relocating block group
> 40865103872 flags 4097
> [ 657.889822] BTRFS info (device sdk1): found 64 extents
> [ 659.190497] BTRFS info (device sdk1): found 64 extents
> [ 659.247765] BTRFS info (device sdk1): relocating block group
> 31201427456 flags 4097
> [ 861.359599] BTRFS info (device sdk1): found 132 extents
> [ 862.875521] BTRFS info (device sdk1): found 132 extents
> [ 862.973499] BTRFS info (device sdk1): relocating block group
> 11874074624 flags 4097
>
>
>
> After the ‚delete missing‘
>
> Label: testpar6 uuid: 79d3c5e4-74ce-4464-a509-ef666dcd9073
> Total devices 15 FS bytes used 31.42GiB
> devid 1 size 146.48GiB used 4.00GiB path /dev/sdh1
> . . .
> devid 14 size 146.48GiB used 4.00GiB path /dev/sdu1
> devid 16 size 146.48GiB used 4.00GiB path /dev/sdv1
>
>
> The md5 checksum is still correct:
>
> root@ubuntu-1204-build:/mnt# md5sum linux-3.14.22.tar
> 80af37cdfb2fa2239f79597c914a8c73 linux-3.14.22.tar
>
>
>
>
>
>
>
>
>
> Hardcore test: PAR6 = 6 parities. Let´s see what happens if i remove five
> disks and replace with with empty ones.
>
> Before i did that the metadata format was converted to PAR6 as well:
>
>
> root@ubuntu-1204-build:~# btrfs fi df /mnt/
> Data, PAR6: total=36.00GiB, used=31.32GiB
> System, PAR6: total=144.00MiB, used=16.00KiB
> Metadata, PAR6: total=1.12GiB, used=101.81MiB
>
>
>
>
> root@ubuntu-1204-build:~# mount /dev/sdn1 /mnt/ -o degraded
>
>
> root@ubuntu-1204-build:~# btrfs fi show
> Label: testpar6 uuid: 79d3c5e4-74ce-4464-a509-ef666dcd9073
> Total devices 15 FS bytes used 31.42GiB
> devid 1 size 146.48GiB used 4.00GiB path
> devid 2 size 146.48GiB used 5.00GiB path
> devid 3 size 146.48GiB used 4.00GiB path
> devid 4 size 146.48GiB used 4.00GiB path
> devid 5 size 146.48GiB used 4.00GiB path
> devid 6 size 146.48GiB used 5.00GiB path /dev/sdm1
> devid 7 size 146.48GiB used 4.03GiB path /dev/sdn1
> devid 8 size 146.48GiB used 4.00GiB path /dev/sdo1
> devid 9 size 146.48GiB used 4.00GiB path /dev/sdp1
> devid 10 size 146.48GiB used 4.00GiB path /dev/sdq1
> devid 11 size 146.48GiB used 4.00GiB path /dev/sdr1
> devid 12 size 146.48GiB used 4.03GiB path /dev/sds1
> devid 13 size 146.48GiB used 4.00GiB path /dev/sdt1
> devid 14 size 146.48GiB used 4.00GiB path /dev/sdu1
> devid 16 size 146.48GiB used 4.00GiB path /dev/sdv1
>
>
> Now let´s bring it back in shape and add five new, empty disks:
>
> btrfs device add /dev/sdh1 /dev/sdi1 /dev/sdj1 /dev/sdk1 /dev/sdl1 /mnt
> btrfs delete missing
> <<wait>>
> root@ubuntu-1204-build:~# btrfs fi show
> Label: testpar6 uuid: 79d3c5e4-74ce-4464-a509-ef666dcd9073
> Total devices 15 FS bytes used 1.09GiB
> devid 6 size 146.48GiB used 2.14GiB path /dev/sdm1
> devid 7 size 146.48GiB used 2.14GiB path /dev/sdn1
> devid 8 size 146.48GiB used 2.14GiB path /dev/sdo1
> devid 9 size 146.48GiB used 2.14GiB path /dev/sdp1
> devid 10 size 146.48GiB used 2.14GiB path /dev/sdq1
> devid 11 size 146.48GiB used 2.14GiB path /dev/sdr1
> devid 12 size 146.48GiB used 2.14GiB path /dev/sds1
> devid 13 size 146.48GiB used 2.14GiB path /dev/sdt1
> devid 14 size 146.48GiB used 2.14GiB path /dev/sdu1
> devid 16 size 146.48GiB used 2.14GiB path /dev/sdv1
> devid 17 size 146.48GiB used 2.14GiB path /dev/sdh1
> devid 18 size 146.48GiB used 2.14GiB path /dev/sdi1
> devid 19 size 146.48GiB used 2.14GiB path /dev/sdj1
> devid 20 size 146.48GiB used 2.14GiB path /dev/sdk1
> devid 21 size 146.48GiB used 2.14GiB path /dev/sdl1
>
>
>
>
>
> And now the checksum:
>
> root@ubuntu-1204-build:/mnt# md5sum linux-3.14.22.tar
> 80af37cdfb2fa2239f79597c914a8c73 linux-3.14.22.tar
>
> Checksum matches!
>
> So.. this looks *very* good to me.
>
>
>
>
>
>
>
>
> Mit freundlichen Grüßen
> Ronny Egner
> --
> Ronny Egner
> Oracle Certified Master 11g (OCM)
>
> Mobile: +49 170 8139903
> EMail: ronnyegner@ronnyegner-consulting.de
> <mailto:roonnyegner@ronnyegner-consulting.de>
>
>
>
>
> Am 21.10.14 09:27 schrieb "NeilBrown" unter <neilb@suse.de>:
>
> >On Tue, 21 Oct 2014 06:33:47 +0000 Ronny Egner
> ><ronnyegner@ronnyegner-consulting.de> wrote:
> >
> >> Dear All,
> >>
> >> i was wondering what happened with the patch posted by Andrea Mazzoleni
> >> back in Februrary 2014 (this Thread:
> >> http://thread.gmane.org/gmane.linux.kernel/1654735).
> >>
> >> Why wash´t it added to the code? Something missing/wrong?
> >>
> >> In my opinion the posted patch is awesome and would enable a unique
> >> feature that no other UNIX-like operating system currently has.
> >>
> >
> >Could you report your test results please.
> >
> >NeilBrown
>

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