Hi Both
Let me add some findings.
The cluster started on an older-than-pacific version - I don't know which
version - and has at some point been migrated to Bluestore.
When running a ceph osd metadata <osd.id>, 50% or so of the OSDs has no data in
the "ceph_version_when_created" the rest has ceph_version_when_created: ceph
version 16.2.....
So I probably have approx. 50% created-pre-pacific OSDs
On a few of the created-pre-pacific OSDs I've executed -
ceph-bluestore-tool --path ./osd.XX show-sharding
With result:
failed to retrieve sharding def
On a few of the others I get results like:
m(3) p(3,0-12) O(3,0-13)=block_cache={type=binned_lru} L P
Also untill now it seems like all the OSD with warnings -
BLUEFS_SPILLOVER
BLUESTORE_SLOW_OP_ALERT (non of these has I/O errors)
Seems to be created-pre-pacific OSDs.
Although I have warnings on a very small percentage of the total number of
OSDs, it might still be a clue.
I will return to the issue tomorrow
________________________________
From: Frédéric Nass <[email protected]>
Sent: Thursday, May 15, 2025 13:43
To: Kasper Rasmussen <[email protected]>; Enrico Bocchi
<[email protected]>
Cc: ceph-users <[email protected]>
Subject: Re: [ceph-users] Re: BLUEFS_SPILLOVER after Reef upgrade
Hi Kasper, Hi Enrico,
You're right, Enrico! I misread the numbers. DB is now 11GB in size, not even
close to 88GB. What probably happened at some point is that RocksDB had to
allocate more space than 88GB, probably during compaction, and overspilled
1.9GB to slow device.
If compacting this OSDs twice in a row doesn't help with getting the 1.9GB back
to fast device, then the below command should:
1/ ceph orch daemon stop osd.${osd}
2/ cephadm shell --fsid $(ceph fsid) --name osd.${osd} -- ceph-bluestore-tool
bluefs-bdev-migrate --path /var/lib/ceph/osd/ceph-${osd} --devs-source
/var/lib/ceph/osd/ceph-${osd}/block --dev-target
/var/lib/ceph/osd/ceph-${osd}/block.db
3/ ceph orch daemon start osd.${osd}
4/ ceph tell osd.${osd} compact
Step 4/ should update bluefs stats figures.
Regarding RocskDB, resharding should not be required as the new layout with
column families is already being used.
Kasper, can you check the value of bluestore_volume_selection_policy for the
overspilled OSDs? It should default to 'use_some_extra' that allows RocksDB to
allocate space between 30GB and 88GB and not overspil to slow device after
allocating ~30GB.
Also, don't forget to enable RocksDB compression.
Regards,
Frédéric.
----- Le 15 Mai 25, à 13:04, Kasper Rasmussen <[email protected]> a
écrit :
Thanks to you both
I was just about to address the used vs total byte thing.
I will look into your pointers Enrico, and return with comments/findings.
________________________________
From: Enrico Bocchi <[email protected]>
Sent: Thursday, May 15, 2025 13:00
To: Kasper Rasmussen <[email protected]>; Frédéric Nass
<[email protected]>
Cc: ceph-users <[email protected]>
Subject: Re: [ceph-users] Re: BLUEFS_SPILLOVER after Reef upgrade
Hi Kasper,
As Frédéric pointed out, you should consider resharding the RocksDB
database to use column families (if the OSD was create pre-pacific):
https://docs.ceph.com/en/latest/rados/configuration/bluestore-config-ref/#rocksdb-sharding
There's additional documentation available with some preliminary steps,
including making sure your RocksDB does not already use column families.
RocksDB options have changed in recent reef releases, and seem to be
quite different w.r.t. Pacific/Quincy. You may want to check if any of
the configuration options that have been modified are relevant for your
setup.
Here is an excellent deep-dive blog post by the unequaled Mark Nelson:
https://ceph.io/en/news/blog/2022/rocksdb-tuning-deep-dive/
For the used vs total bytes I have to disagree with Frédéric (sorry):
11631853568 / 88906653696 gives 13% utilization. So the OSD should not
overspill to slow storage.
I have seen this in the past and rolling back to previous
bluestore_rocksdb options helped. However, I have not resharded RocksDB
to column families yet. Would you please keep us posted if you reshard
to cf and this fixes overspill?
Cheers,
Enrico
On 5/15/25 12:35, Frédéric Nass wrote:
> Hi Kasper,
>
> Thanks for sharing.
>
> I don't see anything wrong with this specific OSD when it comes to
> bluestore_rocksdb_*. It's RocksDB database is using column families and this
> OSD was resharded properly (if not created or recreated in Pacific). What the
> perf dump shows is that the db_used_bytes is above the db_total_bytes. If
> this cluster makes heavy use of metadata (RGW workloads for example) then
> 90GB of DB device for 10TB drives is less than 1% which is not enough.
> General recommendation for RGW workloads is to use a DB device of at least 4%
> in size of the data device [1].
>
> Now, your best move is probably to enable RocksDB compression (ceph config
> set osd bluestore_rocksdb_options_annex 'compression=kLZ4Compression'),
> restart and compact these OSDs to update bluefs stats, and consider giving
> those OSDs larger RocksDB partitions in the future.
>
> Regards,
> Frédéric.
>
> [1]
> https://docs.ceph.com/en/latest/rados/configuration/bluestore-config-ref/#sizing
>
> ----- Le 15 Mai 25, à 7:44, Kasper Rasmussen [email protected] a
> écrit :
>
>> perf dump:
>> "bluefs": {
>> "db_total_bytes": 88906653696,
>> "db_used_bytes": 11631853568,
>> "wal_total_bytes": 0,
>> "wal_used_bytes": 0,
>> "slow_total_bytes": 9796816207872,
>> "slow_used_bytes": 1881341952,
>> "num_files": 229,
>> "log_bytes": 11927552,
>> "log_compactions": 78,
>> "log_write_count": 281792,
>> "logged_bytes": 1154220032,
>> "files_written_wal": 179,
>> "files_written_sst": 311,
>> "write_count_wal": 280405,
>> "write_count_sst": 29432,
>> "bytes_written_wal": 4015595520,
>> "bytes_written_sst": 15728308224,
>> "bytes_written_slow": 2691231744,
>> "max_bytes_wal": 0,
>> "max_bytes_db": 13012828160,
>> "max_bytes_slow": 3146252288,
>> "alloc_unit_slow": 65536,
>> "alloc_unit_db": 1048576,
>> "alloc_unit_wal": 0,
>> "read_random_count": 1871590,
>> "read_random_bytes": 18959576586,
>> "read_random_disk_count": 563421,
>> "read_random_disk_bytes": 17110012647,
>> "read_random_disk_bytes_wal": 0,
>> "read_random_disk_bytes_db": 11373755941,
>> "read_random_disk_bytes_slow": 5736256706,
>> "read_random_buffer_count": 1313456,
>> "read_random_buffer_bytes": 1849563939,
>> "read_count": 275731,
>> "read_bytes": 4825912551,
>> "read_disk_count": 225997,
>> "read_disk_bytes": 4016943104,
>> "read_disk_bytes_wal": 0,
>> "read_disk_bytes_db": 3909947392,
>> "read_disk_bytes_slow": 106999808,
>> "read_prefetch_count": 274534,
>> "read_prefetch_bytes": 4785141168,
>> "write_count": 591760,
>> "write_disk_count": 591838,
>> "write_bytes": 21062987776,
>> "compact_lat": {
>> "avgcount": 78,
>> "sum": 0.572247346,
>> "avgtime": 0.007336504
>> },
>> "compact_lock_lat": {
>> "avgcount": 78,
>> "sum": 0.182746199,
>> "avgtime": 0.002342899
>> },
>> "alloc_slow_fallback": 0,
>> "alloc_slow_size_fallback": 0,
>> "read_zeros_candidate": 0,
>> "read_zeros_errors": 0,
>> "wal_alloc_lat": {
>> "avgcount": 0,
>> "sum": 0.000000000,
>> "avgtime": 0.000000000
>> },
>> "db_alloc_lat": {
>> "avgcount": 969,
>> "sum": 0.006368060,
>> "avgtime": 0.000006571
>> },
>> "slow_alloc_lat": {
>> "avgcount": 39,
>> "sum": 0.004502210,
>> "avgtime": 0.000115441
>> },
>> "alloc_wal_max_lat": 0.000000000,
>> "alloc_db_max_lat": 0.000113831,
>> "alloc_slow_max_lat": 0.000301347
>> },
>>
>>
>> config show:
>> "bluestore_rocksdb_cf": "true",
>> "bluestore_rocksdb_cfs": "m(3) p(3,0-12)
>> O(3,0-13)=block_cache={type=binned_lru}
>> L=min_write_buffer_number_to_merge=32 P=min_write_buffer_number_to_merge=32",
>> "bluestore_rocksdb_options":
>> "compression=kLZ4Compression,max_write_buffer_number=64,min_write_buffer_number_to_merge=6,compaction_style=kCompactionStyleLevel,write_buffer_size=16777216,max_background_jobs=4,level0_file_num_compaction_trigger=8,max_bytes_for_level_base=1073741824,max_bytes_for_level_multiplier=8,compaction_readahead_size=2MB,max_total_wal_size=1073741824,writable_file_max_buffer_size=0",
>> "bluestore_rocksdb_options_annex": "",
>>
>>
>> Dono if it is of any help, but I've compared the config from an OSD not
>> reporting an issues, and there is no difference.
>>
>>
>> ________________________________
>> From: Enrico Bocchi <[email protected]>
>> Sent: Wednesday, May 14, 2025 22:47
>> To: Kasper Rasmussen <[email protected]>; ceph-users
>> <[email protected]>
>> Subject: Re: BLUEFS_SPILLOVER after Reef upgrade
>>
>> Hi Kasper,
>>
>> Would you mind sharing the output of `perf dump` and `config show` from the
>> daemon socket of one of the OSDs reporting blues spillover? I am interested
>> in
>> the bluefs part of the former and in the bluestore_rocksdb options of the
>> latter.
>>
>> The warning about slow ops in bluestore is a different story. There have been
>> several messages on this mailing list recently with suggestions on how to
>> tune
>> the alert threshold. From my experience, they very likely relate to some
>> problem with the underlying storage device, so I'd recommend investigating
>> the
>> root cause rather than simply silencing the warning.
>>
>> Cheers,
>> Enrico
>>
>>
>> ________________________________
>> From: Kasper Rasmussen <[email protected]>
>> Sent: Wednesday, May 14, 2025 8:22:46 PM
>> To: ceph-users <[email protected]>
>> Subject: [ceph-users] BLUEFS_SPILLOVER after Reef upgrade
>>
>> I've just upgraded our ceph cluster from pacific 16.2.15 -> Reef 18.2.7
>>
>> After that I see the warnings:
>>
>> [WRN] BLUEFS_SPILLOVER: 5 OSD(s) experiencing BlueFS spillover
>> osd.110 spilled over 4.5 GiB metadata from 'db' device (8.0 GiB used of
>> 83 GiB)
>> to slow device
>> osd.455 spilled over 1.1 GiB metadata from 'db' device (11 GiB used of
>> 83 GiB)
>> to slow device
>> osd.533 spilled over 426 MiB metadata from 'db' device (10 GiB used of
>> 83 GiB)
>> to slow device
>> osd.560 spilled over 389 MiB metadata from 'db' device (9.8 GiB used of
>> 83 GiB)
>> to slow device
>> osd.597 spilled over 8.6 GiB metadata from 'db' device (7.7 GiB used of
>> 83 GiB)
>> to slow device
>> [WRN] BLUESTORE_SLOW_OP_ALERT: 4 OSD(s) experiencing slow operations in
>> BlueStore
>> osd.410 observed slow operation indications in BlueStore
>> osd.443 observed slow operation indications in BlueStore
>> osd.508 observed slow operation indications in BlueStore
>> osd.593 observed slow operation indications in BlueStore
>>
>> I've tried to run ceph tell osd.XXX compact with no result.
>>
>> Bluefs stats:
>>
>> ceph tell osd.110 bluefs stats
>> 1 : device size 0x14b33fe000 : using 0x202c00000(8.0 GiB)
>> 2 : device size 0x8e8ffc00000 : using 0x5d31d150000(5.8 TiB)
>> RocksDBBlueFSVolumeSelector
>>>> Settings<< extra=0 B, l0_size=1 GiB, l_base=1 GiB, l_multi=8 B
>> DEV/LEV WAL DB SLOW * * REAL
>> FILES
>> LOG 0 B 16 MiB 0 B 0 B 0 B 15
>> MiB
>> 1
>> WAL 0 B 18 MiB 0 B 0 B 0 B 6.3
>> MiB
>> 1
>> DB 0 B 8.0 GiB 0 B 0 B 0 B 8.0
>> GiB
>> 140
>> SLOW 0 B 0 B 4.5 GiB 0 B 0 B 4.5
>> GiB
>> 78
>> TOTAL 0 B 8.0 GiB 4.5 GiB 0 B 0 B 0 B
>> 220
>> MAXIMUMS:
>> LOG 0 B 25 MiB 0 B 0 B 0 B 21
>> MiB
>> WAL 0 B 118 MiB 0 B 0 B 0 B 93
>> MiB
>> DB 0 B 8.2 GiB 0 B 0 B 0 B 8.2
>> GiB
>> SLOW 0 B 0 B 14 GiB 0 B 0 B 14
>> GiB
>> TOTAL 0 B 8.2 GiB 14 GiB 0 B 0 B 0 B
>>>> SIZE << 0 B 79 GiB 8.5 TiB
>> Help with what to do next will, be much appreciated
>>
>>
>> _______________________________________________
>> ceph-users mailing list -- [email protected]
>> To unsubscribe send an email to [email protected]
>>
>> _______________________________________________
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>> To unsubscribe send an email to [email protected]
--
Enrico Bocchi
CERN European Laboratory for Particle Physics
IT - Storage & Data Management - General Storage Services
Mailbox: G20500 - Office: 31-2-010
1211 Genève 23
Switzerland
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