Re: RocksDB and WAL migration to new block device

[Igor Fedotov <ifedotov@xxxxxxx>]

Actually  (given that your devices are already expanded) you don't need 
to expand them once again - one can just update size labels with my new PR.

For new migrations you can use updated bluefs expand command which sets 
size label automatically though.


Thanks,
Igor
On 11/21/2018 11:11 AM, Florian Engelmann wrote:
> Great support Igor!!!! Both thumbs up! We will try to build the tool 
> today and expand those bluefs devices once again.
>
>
> Am 11/20/18 um 6:54 PM schrieb Igor Fedotov:
> > FYI: https://github.com/ceph/ceph/pull/25187
> >
> >
> > On 11/20/2018 8:13 PM, Igor Fedotov wrote:
> > > On 11/20/2018 7:05 PM, Florian Engelmann wrote:
> > > > Am 11/20/18 um 4:59 PM schrieb Igor Fedotov:
> > > > > On 11/20/2018 6:42 PM, Florian Engelmann wrote:
> > > > > > Hi Igor,
> > > > > >
> > > > > > > what's your Ceph version?
> > > > > >
> > > > > > 12.2.8 (SES 5.5 - patched to the latest version)
> > > > > >
> > > > > > > Can you also check the output for
> > > > > > >
> > > > > > > ceph-bluestore-tool show-label -p <path to osd>
> > > > > >
> > > > > > ceph-bluestore-tool show-label --path /var/lib/ceph/osd/ceph-0/
> > > > > > infering bluefs devices from bluestore path
> > > > > > {
> > > > > >     "/var/lib/ceph/osd/ceph-0//block": {
> > > > > >         "osd_uuid": "1e5b3908-20b1-41e4-b6eb-f5636d20450b",
> > > > > >         "size": 8001457295360,
> > > > > >         "btime": "2018-06-29 23:43:12.088842",
> > > > > >         "description": "main",
> > > > > >         "bluefs": "1",
> > > > > >         "ceph_fsid": "a2222146-6561-307e-b032-c5cee2ee520c",
> > > > > >         "kv_backend": "rocksdb",
> > > > > >         "magic": "ceph osd volume v026",
> > > > > >         "mkfs_done": "yes",
> > > > > >         "ready": "ready",
> > > > > >         "whoami": "0"
> > > > > >     },
> > > > > >     "/var/lib/ceph/osd/ceph-0//block.wal": {
> > > > > >         "osd_uuid": "1e5b3908-20b1-41e4-b6eb-f5636d20450b",
> > > > > >         "size": 524288000,
> > > > > >         "btime": "2018-06-29 23:43:12.098690",
> > > > > >         "description": "bluefs wal"
> > > > > >     },
> > > > > >     "/var/lib/ceph/osd/ceph-0//block.db": {
> > > > > >         "osd_uuid": "1e5b3908-20b1-41e4-b6eb-f5636d20450b",
> > > > > >         "size": 524288000,
> > > > > >         "btime": "2018-06-29 23:43:12.098023",
> > > > > >         "description": "bluefs db"
> > > > > >     }
> > > > > > }
> > > > > >
> > > > > >
> > > > > > > It should report 'size' labels for every volume, please check 
> > > > > > > they contain new values.
> > > > > >
> > > > > > That's exactly the problem, whether "ceph-bluestore-tool 
> > > > > > show-label" nor "ceph daemon osd.0 perf dump|jq '.bluefs'" did 
> > > > > > recognize the new sizes. But we are 100% sure the new devices are 
> > > > > > used as we already deleted the old once...
> > > > > >
> > > > > > We tried to delete the "key" "size" to add one with the new value 
> > > > > > but:
> > > > > >
> > > > > > ceph-bluestore-tool rm-label-key --dev 
> > > > > > /var/lib/ceph/osd/ceph-0/block.db -k size
> > > > > > key 'size' not present
> > > > > >
> > > > > > even if:
> > > > > >
> > > > > > ceph-bluestore-tool show-label --dev 
> > > > > > /var/lib/ceph/osd/ceph-0/block.db
> > > > > > {
> > > > > >     "/var/lib/ceph/osd/ceph-0/block.db": {
> > > > > >         "osd_uuid": "1e5b3908-20b1-41e4-b6eb-f5636d20450b",
> > > > > >         "size": 524288000,
> > > > > >         "btime": "2018-06-29 23:43:12.098023",
> > > > > >         "description": "bluefs db"
> > > > > >     }
> > > > > > }
> > > > > >
> > > > > > So it looks like the key "size" is "read-only"?
> > > > > There was a bug in updating specific keys, see
> > > > > https://github.com/ceph/ceph/pull/24352
> > > > >
> > > > > This PR also eliminates the need to set sizes manually on 
> > > > > bdev-expand.
> > > > >
> > > > > I thought it had been backported to Luminous but it looks like it 
> > > > > doesn't.
> > > > > Will submit a PR shortly.
> > > >
> > > > Thank you so much Igor! So we have to decide how to proceed. Maybe 
> > > > you could help us here as well.
> > > >
> > > > Option A: Wait for this fix to be available. -> could last weeks or 
> > > > even months
> > > if you can build a custom version of ceph_bluestore_tool then this 
> > > is a short path. I'll submit a patch today or tomorrow which you 
> > > need to integrate into your private build.
> > > Then you need to upgrade just the tool and apply new sizes.
> > >
> > > > Option B: Recreate OSDs "one-by-one". -> will take a very long time 
> > > > as well
> > > No need for that IMO.
> > > > Option C: There is some "lowlevel" commad allowing us to fix those 
> > > > sizes?
> > > Well hex editor might help here as well. What you need is just to 
> > > update 64bit size value in block.db and block.wal files. In my lab I 
> > > can find it at offset 0x52. Most probably this is the fixed location 
> > > but it's better to check beforehand - existing value should contain 
> > > value corresponding to the one reported with show-label. Or I can do 
> > > that for you - please send the first 4K chunks to me along with 
> > > corresponding label report.
> > > Then update with new values - the field has to contain exactly the 
> > > same size as your new partition.
> > >
> > > > > > > Thanks,
> > > > > > >
> > > > > > > Igor
> > > > > > >
> > > > > > >
> > > > > > > On 11/20/2018 5:29 PM, Florian Engelmann wrote:
> > > > > > > > Hi,
> > > > > > > >
> > > > > > > > today we migrated all of our rocksdb and wal devices to new 
> > > > > > > > once. The new once are much bigger (500MB for wal/db -> 60GB db 
> > > > > > > > and 2G WAL) and LVM based.
> > > > > > > >
> > > > > > > > We migrated like:
> > > > > > > >
> > > > > > > >     export OSD=x
> > > > > > > >
> > > > > > > >     systemctl stop ceph-osd@$OSD
> > > > > > > >
> > > > > > > >     lvcreate -n db-osd$OSD -L60g data || exit 1
> > > > > > > >     lvcreate -n wal-osd$OSD -L2g data || exit 1
> > > > > > > >
> > > > > > > >     dd if=/var/lib/ceph/osd/ceph-$OSD/block.wal 
> > > > > > > > of=/dev/data/wal-osd$OSD bs=1M || exit 1
> > > > > > > >     dd if=/var/lib/ceph/osd/ceph-$OSD/block.db 
> > > > > > > > of=/dev/data/db-osd$OSD bs=1M  || exit 1
> > > > > > > >
> > > > > > > >     rm -v /var/lib/ceph/osd/ceph-$OSD/block.db || exit 1
> > > > > > > >     rm -v /var/lib/ceph/osd/ceph-$OSD/block.wal || exit 1
> > > > > > > >     ln -vs /dev/data/db-osd$OSD 
> > > > > > > > /var/lib/ceph/osd/ceph-$OSD/block.db || exit 1
> > > > > > > >     ln -vs /dev/data/wal-osd$OSD 
> > > > > > > > /var/lib/ceph/osd/ceph-$OSD/block.wal || exit 1
> > > > > > > >
> > > > > > > >
> > > > > > > >     chown -c ceph:ceph $(realpath /dev/data/db-osd$OSD) || exit 1
> > > > > > > >     chown -c ceph:ceph $(realpath /dev/data/wal-osd$OSD) || exit 1
> > > > > > > >     chown -ch ceph:ceph /var/lib/ceph/osd/ceph-$OSD/block.db || 
> > > > > > > > exit 1
> > > > > > > >     chown -ch ceph:ceph /var/lib/ceph/osd/ceph-$OSD/block.wal 
> > > > > > > > || exit 1
> > > > > > > >
> > > > > > > >
> > > > > > > >     ceph-bluestore-tool bluefs-bdev-expand --path 
> > > > > > > > /var/lib/ceph/osd/ceph-$OSD/ || exit 1
> > > > > > > >
> > > > > > > >     systemctl start ceph-osd@$OSD
> > > > > > > >
> > > > > > > >
> > > > > > > > Everything went fine but it looks like the db and wal size is 
> > > > > > > > still the old one:
> > > > > > > >
> > > > > > > > ceph daemon osd.0 perf dump|jq '.bluefs'
> > > > > > > > {
> > > > > > > >   "gift_bytes": 0,
> > > > > > > >   "reclaim_bytes": 0,
> > > > > > > >   "db_total_bytes": 524279808,
> > > > > > > >   "db_used_bytes": 330301440,
> > > > > > > >   "wal_total_bytes": 524283904,
> > > > > > > >   "wal_used_bytes": 69206016,
> > > > > > > >   "slow_total_bytes": 320058949632,
> > > > > > > >   "slow_used_bytes": 13606322176,
> > > > > > > >   "num_files": 220,
> > > > > > > >   "log_bytes": 44204032,
> > > > > > > >   "log_compactions": 0,
> > > > > > > >   "logged_bytes": 31145984,
> > > > > > > >   "files_written_wal": 1,
> > > > > > > >   "files_written_sst": 1,
> > > > > > > >   "bytes_written_wal": 37753489,
> > > > > > > >   "bytes_written_sst": 238992
> > > > > > > > }
> > > > > > > >
> > > > > > > >
> > > > > > > > Even if the new block devices are recognized correctly:
> > > > > > > >
> > > > > > > > 2018-11-20 11:40:34.653524 7f70219b8d00  1 bdev(0x5647ea9ce200 
> > > > > > > > /var/lib/ceph/osd/ceph-0/block.db) open size 64424509440 
> > > > > > > > (0xf00000000, 60GiB) block_size 4096 (4KiB) non-rotational
> > > > > > > > 2018-11-20 11:40:34.653532 7f70219b8d00  1 bluefs 
> > > > > > > > add_block_device bdev 1 path /var/lib/ceph/osd/ceph-0/block.db 
> > > > > > > > size 60GiB
> > > > > > > >
> > > > > > > >
> > > > > > > > 2018-11-20 11:40:34.662385 7f70219b8d00  1 bdev(0x5647ea9ce600 
> > > > > > > > /var/lib/ceph/osd/ceph-0/block.wal) open size 2147483648 
> > > > > > > > (0x80000000, 2GiB) block_size 4096 (4KiB) non-rotational
> > > > > > > > 2018-11-20 11:40:34.662406 7f70219b8d00  1 bluefs 
> > > > > > > > add_block_device bdev 0 path /var/lib/ceph/osd/ceph-0/block.wal 
> > > > > > > > size 2GiB
> > > > > > > >
> > > > > > > >
> > > > > > > > Are we missing some command to "notify" rocksdb about the new 
> > > > > > > > device size?
> > > > > > > >
> > > > > > > > All the best,
> > > > > > > > Florian
> > > > > > > >
> > > > > > > >
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> > > > > >
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