[ceph-users] Re: down OSDs, Bluestore out of space, unable to restart

26 Nov 2024

      Got it, the perf dump can give information:
ceph daemon osd.x perf dump|jq .bluefs

________________________________
From: Szabo, Istvan (Agoda) <Istvan.Szabo@agoda.com>
Sent: Wednesday, November 27, 2024 9:20 AM
To: Frédéric Nass <frederic.nass@univ-lorraine.fr>; John Jasen <jjasen@gmail.com>; Igor Fedotov <igor.fedotov@croit.io>
Cc: ceph-users <ceph-users@ceph.io>
Subject: [ceph-users] Re: down OSDs, Bluestore out of space, unable to restart

Hi,

Is there a way to check without shutting down an osd the remaining free space on the co-located osd how much has left for DB or how full is it?

________________________________
From: Frédéric Nass <frederic.nass@univ-lorraine.fr>
Sent: Wednesday, November 27, 2024 6:11 AM
To: John Jasen <jjasen@gmail.com>
Cc: Igor Fedotov <igor.fedotov@croit.io>; ceph-users <ceph-users@ceph.io>
Subject: [ceph-users] Re: down OSDs, Bluestore out of space, unable to restart

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________________________________

Hi John,

That's about right. Two potential solutions exist:
1. Adding a new drive to the server and sharing it for RocksDB metadata, or
2. Repurposing one of the failed OSDs for the same purpose (if adding more drives isn't feasible).

Igor's post #6 [1] explains the challenges with co-located OSDs (DB+WAL+data on the same device) when they run out of space, where significant fragmentation occurs and BlueFS and BlueStore block sizes are misaligned. The solution (included in 17.2.6) was to allow BlueFS to allocate 4k extents when it couldn't find 64k contiguous extents. However, it seems that even with this fix, these OSDs still can't boot up.

Therefore, the recommendation is to extend the RocksDB volume to another device as a temporary workaround.

Before proceeding, I recommend checking the failed OSDs' bluefs_shared_alloc_size value. If it's 64k, you might want to try lowering this to 32k or even 4k, as some users reported [2] that reducing this value helped failed OSDs boot up and remain stable for a period of time. Might be worth checking and trying.

Regards,
Frédéric.

[1] https://tracker.ceph.com/issues/53466#note-6
[2] https://github.com/rook/rook/issues/9885#issuecomment-1761076861"

________________________________
De : John Jasen <jjasen@gmail.com>
Envoyé : mardi 26 novembre 2024 18:50
À : Igor Fedotov
Cc: ceph-users
Objet : [ceph-users] Re: down OSDs, Bluestore out of space, unable to restart

Let me see if I have the approach right'ish:

scrounge some more disk for the servers with full/down OSDs.
partition the new disks into LVs for each downed OSD.
Attach as a lvm new-db to the downed OSDs.
Restart the OSDs.
Profit.

Is that about right?

On Tue, Nov 26, 2024 at 11:28 AM Igor Fedotov <igor.fedotov@croit.io> wrote:
...
Well, so there is a single shared volume (disk) per OSD, right?
If so one can add dedicated DB volume to such an OSD - one done OSD will
have two underlying devices: main(which is original shared disk) and new
dedicated DB ones.  And hence this will effectively provide additional
space for BlueFS/RocksDB and permit OSD to start up.
I'm not aware of all the details how to do that with cephadm (or whatever
RH uses) but on bare metal setup this could be achieved by issuing
'ceph-volume lvm new-db' command which will attach new LV (provided by
user) to specific OSD.
Thanks,
Igor
On 26.11.2024 19:16, John Jasen wrote:
They're all bluefs_single_shared_device, if I understand your question.
There's no room left on the devices to expand.
We started at quincy with this cluster, and didn't vary too much from the
Redhat Ceph storage 6 documentation for setting it up.
On Tue, Nov 26, 2024 at 4:48 AM Igor Fedotov <igor.fedotov@croit.io>
wrote:
...
Hi John,
you haven't described your OSD volume configuration but you might want
to try adding standalone DB volume if OSD uses LVM and has single main
device only.
'ceph-volume lvm new-db' command is the preferred way of doing that, see
https://docs.ceph.com/en/quincy/ceph-volume/lvm/newdb/
Thanks,
Igor
On 25.11.2024 21:37, John Jasen wrote:
...
Ceph version 17.2.6
After a power loss event affecting my ceph cluster, I've been putting
humpty dumpty back together since.
One problem I face is that with objects degraded, rebalancing doesn't
run
-- and this resulted in several of my fast OSDs filling up.
I have 8 OSDs currently down, 100% full (exceeding all the full ratio
settings on by default or I toggled to try and keep it together), and
when
I try to restart them, they fail out. Is there any way to bring these
back
from the dead?
Here's some interesting output from journalctl -xeu on the failed OSD:
ceph-osd[2383080]: bluestore::NCB::__restore_allocator::No Valid
allocation
info on disk (empty file)
ceph-osd[2383080]: bluestore(/var/lib/ceph/osd/ceph-242)
_init_alloc::NCB::restore_allocator() failed! Run Full Recovery from
ONodes
(might take a while) ...
ceph-osd[2389725]: bluefs _allocate allocation failed, needed 0x3000
ceph-6ab85342-53d6-11ee-88a7-e43d1a153e91-osd-242[2389718]:     -2>
2024-11-25T18:31:42.070+0000 7f0adfdef540 -1 bluefs _flush_range_F
allocated: 0x0 offset: 0x0 length: 0x230f
ceph-osd[2389725]: bluefs _flush_range_F allocated: 0x0 offset: 0x0
length:
0x230f
Followed quickly by an abort:
/home/jenkins-build/build/workspace/ceph-build/ARCH/x86_64/AVAILABLE_ARCH/x86_64/AVAILABLE_DIST/centos8/DIST/centos8/MACHINE_SIZE/gigantic/release/17.2.6/rpm/el8/BUILD/ceph-17.2.6/src/os/bluestore/BlueFS.cc:
...
In funct>
/home/jenkins-build/build/workspace/ceph-build/ARCH/x86_64/AVAILABLE_ARCH/x86_64/AVAILABLE_DIST/centos8/DIST/centos8/MACHINE_SIZE/gigantic/release/17.2.6/rpm/el8/BUILD/ceph-17.2.6/src/os/bluestore/BlueFS.cc:
...
3380: ce>
ceph
version
17.2.6 (d7ff0d10654d2280e08f1ab989c7cdf3064446a5) quincy (stable)
                                                              1:
(ceph::__ceph_abort(char const*, int, char const*,
std::__cxx11::basic_string<char, std::char_traits<char>,
std::allocator<char> > const&)+0xd7) [0x559bf4361d2f]
                                                              2:
(BlueFS::_flush_range_F(BlueFS::FileWriter*, unsigned long, unsigned
long)+0x7a9) [0x559bf4b225f9]
                                                              3:
(BlueFS::_flush_F(BlueFS::FileWriter*, bool, bool*)+0xa2)
[0x559bf4b22812]
                                                              4:
(BlueFS::fsync(BlueFS::FileWriter*)+0x8e) [0x559bf4b40c3e]
                                                              5:
(BlueRocksWritableFile::Sync()+0x19) [0x559bf4b51ed9]
                                                              6:
(rocksdb::LegacyWritableFileWrapper::Sync(rocksdb::IOOptions const&,
rocksdb::IODebugContext*)+0x22) [0x559bf507fbd2]
                                                              7:
(rocksdb::WritableFileWriter::SyncInternal(bool)+0x5aa) [0x559bf51a880a]
                                                              8:
(rocksdb::WritableFileWriter::Sync(bool)+0x100) [0x559bf51aa0a0]
                                                              9:
(rocksdb::SyncManifest(rocksdb::Env*, rocksdb::ImmutableDBOptions
const*,
rocksdb::WritableFileWriter*)+0x10b) [0x559bf51a3bfb]
                                                              10:
(rocksdb::VersionSet::ProcessManifestWrites(std::deque<rocksdb::VersionSet::ManifestWriter,
...
std::allocator<rocksdb::VersionSet::ManifestWriter> >&,
rocksdb::InstrumentedMutex*, rocksdb::FSDirectory*, bool, rocks>
                                                              11:
(rocksdb::VersionSet::LogAndApply(rocksdb::autovector<rocksdb::ColumnFamilyData*,
...
8ul> const&, rocksdb::autovector<rocksdb::MutableCFOptions const*, 8ul>
const&, rocksdb::autovector<rocksdb::autovector<rocksdb::>
                                                              12:
(rocksdb::VersionSet::LogAndApply(rocksdb::ColumnFamilyData*,
rocksdb::MutableCFOptions const&, rocksdb::VersionEdit*,
rocksdb::InstrumentedMutex*, rocksdb::FSDirectory*, bool,
rocksdb::ColumnFamilyOptions const>
                                                              13:
(rocksdb::DBImpl::DeleteUnreferencedSstFiles()+0xa30) [0x559bf50bd250]
                                                              14:
(rocksdb::DBImpl::Recover(std::vector<rocksdb::ColumnFamilyDescriptor,
std::allocator<rocksdb::ColumnFamilyDescriptor> > const&, bool, bool,
bool,
unsigned long*)+0x13f1) [0x559bf50d3f21]
                                                              15:
(rocksdb::DBImpl::Open(rocksdb::DBOptions const&,
std::__cxx11::basic_string<char, std::char_traits<char>,
std::allocator<char> > const&,
std::vector<rocksdb::ColumnFamilyDescriptor,
std::allocator<rocksdb::Colu>
                                                              16:
(rocksdb::DB::Open(rocksdb::DBOptions const&,
std::__cxx11::basic_string<char, std::char_traits<char>,
std::allocator<char> > const&,
std::vector<rocksdb::ColumnFamilyDescriptor,
std::allocator<rocksdb::ColumnFa>
                                                              17:
(RocksDBStore::do_open(std::ostream&, bool, bool,
std::__cxx11::basic_string<char, std::char_traits<char>,
std::allocator<char> > const&)+0x77a) [0x559bf503766a]
                                                              18:
(BlueStore::_open_db(bool, bool, bool)+0xbb4) [0x559bf4a4bff4]
                                                              19:
(BlueStore::_open_db_and_around(bool, bool)+0x500) [0x559bf4a766e0]
                                                              20:
(BlueStore::_mount()+0x396) [0x559bf4a795d6]
                                                              21:
(OSD::init()+0x556) [0x559bf44a0eb6]
                                                              22: main()
                                                              23:
__libc_start_main()
                                                              24:
_start()
*** Caught signal (Aborted) **
                                                              in thread
7f0adfdef540 thread_name:ceph-osd
ceph
version
17.2.6 (d7ff0d10654d2280e08f1ab989c7cdf3064446a5) quincy (stable)
                                                              1:
/lib64/libpthread.so.0(+0x12cf0) [0x7f0addff1cf0]
                                                              2:
gsignal()
                                                              3: abort()
                                                              4:
(ceph::__ceph_abort(char const*, int, char const*,
std::__cxx11::basic_string<char, std::char_traits<char>,
std::allocator<char> > const&)+0x197) [0x559bf4361def]
                                                              5:
(BlueFS::_flush_range_F(BlueFS::FileWriter*, unsigned long, unsigned
long)+0x7a9) [0x559bf4b225f9]
                                                              6:
(BlueFS::_flush_F(BlueFS::FileWriter*, bool, bool*)+0xa2)
[0x559bf4b22812]
                                                              7:
(BlueFS::fsync(BlueFS::FileWriter*)+0x8e) [0x559bf4b40c3e]
                                                              8:
(BlueRocksWritableFile::Sync()+0x19) [0x559bf4b51ed9]
                                                              9:
(rocksdb::LegacyWritableFileWrapper::Sync(rocksdb::IOOptions const&,
rocksdb::IODebugContext*)+0x22) [0x559bf507fbd2]
                                                              10:
(rocksdb::WritableFileWriter::SyncInternal(bool)+0x5aa) [0x559bf51a880a]
                                                              11:
(rocksdb::WritableFileWriter::Sync(bool)+0x100) [0x559bf51aa0a0]
                                                              12:
(rocksdb::SyncManifest(rocksdb::Env*, rocksdb::ImmutableDBOptions
const*,
rocksdb::WritableFileWriter*)+0x10b) [0x559bf51a3bfb]
                                                              13:
(rocksdb::VersionSet::ProcessManifestWrites(std::deque<rocksdb::VersionSet::ManifestWriter,
...
std::allocator<rocksdb::VersionSet::ManifestWriter> >&,
rocksdb::InstrumentedMutex*, rocksdb::FSDirectory*, bool, rocks>
                                                              14:
(rocksdb::VersionSet::LogAndApply(rocksdb::autovector<rocksdb::ColumnFamilyData*,
...
8ul> const&, rocksdb::autovector<rocksdb::MutableCFOptions const*, 8ul>
const&, rocksdb::autovector<rocksdb::autovector<rocksdb::>
                                                              15:
(rocksdb::VersionSet::LogAndApply(rocksdb::ColumnFamilyData*,
rocksdb::MutableCFOptions const&, rocksdb::VersionEdit*,
rocksdb::InstrumentedMutex*, rocksdb::FSDirectory*, bool,
rocksdb::ColumnFamilyOptions const>
                                                              16:
(rocksdb::DBImpl::DeleteUnreferencedSstFiles()+0xa30) [0x559bf50bd250]
                                                              17:
(rocksdb::DBImpl::Recover(std::vector<rocksdb::ColumnFamilyDescriptor,
std::allocator<rocksdb::ColumnFamilyDescriptor> > const&, bool, bool,
bool,
unsigned long*)+0x13f1) [0x559bf50d3f21]
                                                              18:
(rocksdb::DBImpl::Open(rocksdb::DBOptions const&,
std::__cxx11::basic_string<char, std::char_traits<char>,
std::allocator<char> > const&,
std::vector<rocksdb::ColumnFamilyDescriptor,
std::allocator<rocksdb::Colu>
                                                              19:
(rocksdb::DB::Open(rocksdb::DBOptions const&,
std::__cxx11::basic_string<char, std::char_traits<char>,
std::allocator<char> > const&,
std::vector<rocksdb::ColumnFamilyDescriptor,
std::allocator<rocksdb::ColumnFa>
                                                              20:
(RocksDBStore::do_open(std::ostream&, bool, bool,
std::__cxx11::basic_string<char, std::char_traits<char>,
std::allocator<char> > const&)+0x77a) [0x559bf503766a]
                                                              21:
(BlueStore::_open_db(bool, bool, bool)+0xbb4) [0x559bf4a4bff4]
                                                              22:
(BlueStore::_open_db_and_around(bool, bool)+0x500) [0x559bf4a766e0]
                                                              23:
(BlueStore::_mount()+0x396) [0x559bf4a795d6]
                                                              24:
(OSD::init()+0x556) [0x559bf44a0eb6]
                                                              25: main()
                                                              26:
__libc_start_main()
                                                              27:
_start()
                                                              NOTE: a
copy
of the executable, or `objdump -rdS <executable>` is needed to interpret
this.
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