On Fri, 6 Oct 2017 09:14:40 -0700 Shawfeng Dong wrote: > I found the command: rados -p cephfs_cache cache-flush-evict-all > That's not what you want/need. Though it will fix your current "full" issue. > The documentation ( > http://docs.ceph.com/docs/luminous/rados/operations/cache-tiering/) has > been improved a lot since I last checked it a few weeks ago! > The need to set max_bytes and max_objects has been documented for ages (since Hammer). more below... > -Shaw > > On Fri, Oct 6, 2017 at 9:10 AM, Shawfeng Dong <shaw@xxxxxxxx> wrote: > > > Thanks, Luis. > > > > I've just set max_bytes and max_objects: How? Editing the conf file won't help until a restart. > > target_max_objects: 1000000 (1M) > > target_max_bytes: 1099511627776 (1TB) > I'd lower that or the cache_target_full_ratio by another 10%. Christian > > > > but nothing appears to be happening. Is there a way to force flushing? > > > > Thanks, > > Shaw > > > > On Fri, Oct 6, 2017 at 8:55 AM, Luis Periquito <periquito@xxxxxxxxx> > > wrote: > > > >> Not looking at anything else, you didn't set the max_bytes or > >> max_objects for it to start flushing... > >> > >> On Fri, Oct 6, 2017 at 4:49 PM, Shawfeng Dong <shaw@xxxxxxxx> wrote: > >> > Dear all, > >> > > >> > Thanks a lot for the very insightful comments/suggestions! > >> > > >> > There are 3 OSD servers in our pilot Ceph cluster, each with 2x 1TB SSDs > >> > (boot disks), 12x 8TB SATA HDDs and 2x 1.2TB NVMe SSDs. We use the > >> bluestore > >> > backend, with the first NVMe as the WAL and DB devices for OSDs on the > >> HDDs. > >> > And we try to create a cache tier out of the second NVMes. > >> > > >> > Here are the outputs of the commands suggested by David: > >> > > >> > 1) # ceph df > >> > GLOBAL: > >> > SIZE AVAIL RAW USED %RAW USED > >> > 265T 262T 2847G 1.05 > >> > POOLS: > >> > NAME ID USED %USED MAX AVAIL > >> OBJECTS > >> > cephfs_data 1 0 0 248T > >> 0 > >> > cephfs_metadata 2 8515k 0 248T > >> 24 > >> > cephfs_cache 3 1381G 100.00 0 > >> 355385 > >> > > >> > 2) # ceph osd df > >> > 0 hdd 7.27829 1.00000 7452G 2076M 7450G 0.03 0.03 174 > >> > 1 hdd 7.27829 1.00000 7452G 2072M 7450G 0.03 0.03 169 > >> > 2 hdd 7.27829 1.00000 7452G 2072M 7450G 0.03 0.03 173 > >> > 3 hdd 7.27829 1.00000 7452G 2072M 7450G 0.03 0.03 159 > >> > 4 hdd 7.27829 1.00000 7452G 2072M 7450G 0.03 0.03 173 > >> > 5 hdd 7.27829 1.00000 7452G 2072M 7450G 0.03 0.03 162 > >> > 6 hdd 7.27829 1.00000 7452G 2072M 7450G 0.03 0.03 149 > >> > 7 hdd 7.27829 1.00000 7452G 2072M 7450G 0.03 0.03 179 > >> > 8 hdd 7.27829 1.00000 7452G 2076M 7450G 0.03 0.03 163 > >> > 9 hdd 7.27829 1.00000 7452G 2072M 7450G 0.03 0.03 194 > >> > 10 hdd 7.27829 1.00000 7452G 2072M 7450G 0.03 0.03 185 > >> > 11 hdd 7.27829 1.00000 7452G 2072M 7450G 0.03 0.03 168 > >> > 36 nvme 1.09149 1.00000 1117G 855G 262G 76.53 73.01 79 > >> > 12 hdd 7.27829 1.00000 7452G 2072M 7450G 0.03 0.03 180 > >> > 13 hdd 7.27829 1.00000 7452G 2072M 7450G 0.03 0.03 168 > >> > 14 hdd 7.27829 1.00000 7452G 2072M 7450G 0.03 0.03 178 > >> > 15 hdd 7.27829 1.00000 7452G 2072M 7450G 0.03 0.03 170 > >> > 16 hdd 7.27829 1.00000 7452G 2072M 7450G 0.03 0.03 149 > >> > 17 hdd 7.27829 1.00000 7452G 2072M 7450G 0.03 0.03 203 > >> > 18 hdd 7.27829 1.00000 7452G 2072M 7450G 0.03 0.03 173 > >> > 19 hdd 7.27829 1.00000 7452G 2076M 7450G 0.03 0.03 158 > >> > 20 hdd 7.27829 1.00000 7452G 2072M 7450G 0.03 0.03 154 > >> > 21 hdd 7.27829 1.00000 7452G 2072M 7450G 0.03 0.03 160 > >> > 22 hdd 7.27829 1.00000 7452G 2072M 7450G 0.03 0.03 167 > >> > 23 hdd 7.27829 1.00000 7452G 2076M 7450G 0.03 0.03 188 > >> > 37 nvme 1.09149 1.00000 1117G 1061G 57214M 95.00 90.63 98 > >> > 24 hdd 7.27829 1.00000 7452G 2072M 7450G 0.03 0.03 187 > >> > 25 hdd 7.27829 1.00000 7452G 2072M 7450G 0.03 0.03 200 > >> > 26 hdd 7.27829 1.00000 7452G 2072M 7450G 0.03 0.03 147 > >> > 27 hdd 7.27829 1.00000 7452G 2072M 7450G 0.03 0.03 171 > >> > 28 hdd 7.27829 1.00000 7452G 2072M 7450G 0.03 0.03 162 > >> > 29 hdd 7.27829 1.00000 7452G 2072M 7450G 0.03 0.03 152 > >> > 30 hdd 7.27829 1.00000 7452G 2072M 7450G 0.03 0.03 174 > >> > 31 hdd 7.27829 1.00000 7452G 2072M 7450G 0.03 0.03 176 > >> > 32 hdd 7.27829 1.00000 7452G 2072M 7450G 0.03 0.03 182 > >> > 33 hdd 7.27829 1.00000 7452G 2072M 7450G 0.03 0.03 155 > >> > 34 hdd 7.27829 1.00000 7452G 2076M 7450G 0.03 0.03 166 > >> > 35 hdd 7.27829 1.00000 7452G 2076M 7450G 0.03 0.03 176 > >> > 38 nvme 1.09149 1.00000 1117G 857G 260G 76.71 73.18 79 > >> > TOTAL 265T 2847G 262T 1.05 > >> > MIN/MAX VAR: 0.03/90.63 STDDEV: 22.81 > >> > > >> > 3) # ceph osd tree > >> > -1 265.29291 root default > >> > -3 88.43097 host pulpo-osd01 > >> > 0 hdd 7.27829 osd.0 up 1.00000 1.00000 > >> > 1 hdd 7.27829 osd.1 up 1.00000 1.00000 > >> > 2 hdd 7.27829 osd.2 up 1.00000 1.00000 > >> > 3 hdd 7.27829 osd.3 up 1.00000 1.00000 > >> > 4 hdd 7.27829 osd.4 up 1.00000 1.00000 > >> > 5 hdd 7.27829 osd.5 up 1.00000 1.00000 > >> > 6 hdd 7.27829 osd.6 up 1.00000 1.00000 > >> > 7 hdd 7.27829 osd.7 up 1.00000 1.00000 > >> > 8 hdd 7.27829 osd.8 up 1.00000 1.00000 > >> > 9 hdd 7.27829 osd.9 up 1.00000 1.00000 > >> > 10 hdd 7.27829 osd.10 up 1.00000 1.00000 > >> > 11 hdd 7.27829 osd.11 up 1.00000 1.00000 > >> > 36 nvme 1.09149 osd.36 up 1.00000 1.00000 > >> > -5 88.43097 host pulpo-osd02 > >> > 12 hdd 7.27829 osd.12 up 1.00000 1.00000 > >> > 13 hdd 7.27829 osd.13 up 1.00000 1.00000 > >> > 14 hdd 7.27829 osd.14 up 1.00000 1.00000 > >> > 15 hdd 7.27829 osd.15 up 1.00000 1.00000 > >> > 16 hdd 7.27829 osd.16 up 1.00000 1.00000 > >> > 17 hdd 7.27829 osd.17 up 1.00000 1.00000 > >> > 18 hdd 7.27829 osd.18 up 1.00000 1.00000 > >> > 19 hdd 7.27829 osd.19 up 1.00000 1.00000 > >> > 20 hdd 7.27829 osd.20 up 1.00000 1.00000 > >> > 21 hdd 7.27829 osd.21 up 1.00000 1.00000 > >> > 22 hdd 7.27829 osd.22 up 1.00000 1.00000 > >> > 23 hdd 7.27829 osd.23 up 1.00000 1.00000 > >> > 37 nvme 1.09149 osd.37 up 1.00000 1.00000 > >> > 36 nvme 1.09149 osd.36 up 1.00000 1.00000 > >> > -5 88.43097 host pulpo-osd02 > >> > 12 hdd 7.27829 osd.12 up 1.00000 1.00000 > >> > 13 hdd 7.27829 osd.13 up 1.00000 1.00000 > >> > 14 hdd 7.27829 osd.14 up 1.00000 1.00000 > >> > 15 hdd 7.27829 osd.15 up 1.00000 1.00000 > >> > 16 hdd 7.27829 osd.16 up 1.00000 1.00000 > >> > 17 hdd 7.27829 osd.17 up 1.00000 1.00000 > >> > 18 hdd 7.27829 osd.18 up 1.00000 1.00000 > >> > 19 hdd 7.27829 osd.19 up 1.00000 1.00000 > >> > 20 hdd 7.27829 osd.20 up 1.00000 1.00000 > >> > 21 hdd 7.27829 osd.21 up 1.00000 1.00000 > >> > 22 hdd 7.27829 osd.22 up 1.00000 1.00000 > >> > 23 hdd 7.27829 osd.23 up 1.00000 1.00000 > >> > 37 nvme 1.09149 osd.37 up 1.00000 1.00000 > >> > -7 88.43097 host pulpo-osd03 > >> > 24 hdd 7.27829 osd.24 up 1.00000 1.00000 > >> > 25 hdd 7.27829 osd.25 up 1.00000 1.00000 > >> > 26 hdd 7.27829 osd.26 up 1.00000 1.00000 > >> > 27 hdd 7.27829 osd.27 up 1.00000 1.00000 > >> > 28 hdd 7.27829 osd.28 up 1.00000 1.00000 > >> > 29 hdd 7.27829 osd.29 up 1.00000 1.00000 > >> > 30 hdd 7.27829 osd.30 up 1.00000 1.00000 > >> > 31 hdd 7.27829 osd.31 up 1.00000 1.00000 > >> > 32 hdd 7.27829 osd.32 up 1.00000 1.00000 > >> > 33 hdd 7.27829 osd.33 up 1.00000 1.00000 > >> > 34 hdd 7.27829 osd.34 up 1.00000 1.00000 > >> > 35 hdd 7.27829 osd.35 up 1.00000 1.00000 > >> > 38 nvme 1.09149 osd.38 up 1.00000 1.00000 > >> > > >> > 4) # ceph osd pool get cephfs_cache all > >> > min_size: 2 > >> > crash_replay_interval: 0 > >> > pg_num: 128 > >> > pgp_num: 128 > >> > crush_rule: pulpo_nvme > >> > hashpspool: true > >> > nodelete: false > >> > nopgchange: false > >> > nosizechange: false > >> > write_fadvise_dontneed: false > >> > noscrub: false > >> > nodeep-scrub: false > >> > hit_set_type: bloom > >> > hit_set_period: 14400 > >> > hit_set_count: 12 > >> > hit_set_fpp: 0.05 > >> > use_gmt_hitset: 1 > >> > auid: 0 > >> > target_max_objects: 0 > >> > target_max_bytes: 0 > >> > cache_target_dirty_ratio: 0.4 > >> > cache_target_dirty_high_ratio: 0.6 > >> > cache_target_full_ratio: 0.8 > >> > cache_min_flush_age: 0 > >> > cache_min_evict_age: 0 > >> > min_read_recency_for_promote: 0 > >> > min_write_recency_for_promote: 0 > >> > fast_read: 0 > >> > hit_set_grade_decay_rate: 0 > >> > crash_replay_interval: 0 > >> > > >> > Do you see anything wrong? We had written some small files to the CephFS > >> > before we tried to write the big 1TB file. What is puzzling to me is > >> that no > >> > data has been written back to the data pool. > >> > > >> > Best, > >> > Shaw > >> > > >> > On Fri, Oct 6, 2017 at 6:46 AM, David Turner <drakonstein@xxxxxxxxx> > >> wrote: > >> >> > >> >> > >> >> > >> >> On Fri, Oct 6, 2017, 1:05 AM Christian Balzer <chibi@xxxxxxx> wrote: > >> >>> > >> >>> > >> >>> Hello, > >> >>> > >> >>> On Fri, 06 Oct 2017 03:30:41 +0000 David Turner wrote: > >> >>> > >> >>> > You're missing most all of the important bits. What the osds in your > >> >>> > cluster look like, your tree, and your cache pool settings. > >> >>> > > >> >>> > ceph df > >> >>> > ceph osd df > >> >>> > ceph osd tree > >> >>> > ceph osd pool get cephfs_cache all > >> >>> > > >> >>> Especially the last one. > >> >>> > >> >>> My money is on not having set target_max_objects and target_max_bytes > >> to > >> >>> sensible values along with the ratios. > >> >>> In short, not having read the (albeit spotty) documentation. > >> >>> > >> >>> > You have your writeback cache on 3 nvme drives. It looks like you > >> have > >> >>> > 1.6TB available between them for the cache. I don't know the > >> behavior > >> >>> > of a > >> >>> > writeback cache tier on cephfs for large files, but I would guess > >> that > >> >>> > it > >> >>> > can only hold full files and not flush partial files. > >> >>> > >> >>> I VERY much doubt that, if so it would be a massive flaw. > >> >>> One assumes that cache operations work on the RADOS object level, no > >> >>> matter what. > >> >> > >> >> I hope that it is on the rados level, but not a single object had been > >> >> flushed to the backing pool. So I hazarded a guess. Seeing his > >> settings will > >> >> shed more light. > >> >>> > >> >>> > >> >>> > That would mean your > >> >>> > cache needs to have enough space for any file being written to the > >> >>> > cluster. > >> >>> > In this case a 1.3TB file with 3x replication would require 3.9TB > >> (more > >> >>> > than double what you have available) of available space in your > >> >>> > writeback > >> >>> > cache. > >> >>> > > >> >>> > There are very few use cases that benefit from a cache tier. The > >> docs > >> >>> > for > >> >>> > Luminous warn as much. > >> >>> You keep repeating that like a broken record. > >> >>> > >> >>> And while certainly not false I for one wouldn't be able to use > >> (justify > >> >>> using) Ceph w/o cache tiers in our main use case. > >> >>> > >> >>> > >> >>> In this case I assume they were following and old cheat sheet or such, > >> >>> suggesting the previously required cache tier with EC pools. > >> >> > >> >> > >> >> http://docs.ceph.com/docs/luminous/rados/operations/cache-tiering/ > >> >> > >> >> I know I keep repeating it, especially recently as there have been a > >> lot > >> >> of people asking about it. The Luminous docs added a large section > >> about how > >> >> it is probably not what you want. Like me, it is not saying that there > >> are > >> >> no use cases for it. There was no information provided about the use > >> case > >> >> and I made some suggestions/guesses. I'm also guessing that they are > >> >> following a guide where a writeback cache was necessary for CephFS to > >> use EC > >> >> prior to Luminous. I also usually add that people should test it out > >> and > >> >> find what works best for them. I will always defer to your practical > >> use of > >> >> cache tiers as well, especially when using rbds. > >> >> > >> >> I manage a cluster that I intend to continue running a writeback cache > >> in > >> >> front of CephFS on the same drives as the EC pool. The use case > >> receives a > >> >> good enough benefit from the cache tier that it isn't even required to > >> use > >> >> flash media to see it. It is used for video editing and the files are > >> >> usually modified and read within the first 24 hours and then left in > >> cold > >> >> storage until deleted. I have the cache timed to keep everything in it > >> for > >> >> 24 hours and then evict it by using a minimum time to flush and evict > >> at 24 > >> >> hours and a target max bytes of 0. All files are in there for that > >> time and > >> >> then it never has to decide what to keep as it doesn't keep anything > >> longer > >> >> than that. Luckily read performance from cold storage is not a > >> requirement > >> >> of this cluster as any read operation has to first read it from EC > >> storage, > >> >> write it to replica storage, and then read it from replica storage... > >> Yuck. > >> >>> > >> >>> > >> >>> Christian > >> >>> > >> >>> >What is your goal by implementing this cache? If the > >> >>> > answer is to utilize extra space on the nvmes, then just remove it > >> and > >> >>> > say > >> >>> > thank you. The better use of nvmes in that case are as a part of the > >> >>> > bluestore stack and give your osds larger DB partitions. Keeping > >> your > >> >>> > metadata pool on nvmes is still a good idea. > >> >>> > > >> >>> > On Thu, Oct 5, 2017, 7:45 PM Shawfeng Dong <shaw@xxxxxxxx> wrote: > >> >>> > > >> >>> > > Dear all, > >> >>> > > > >> >>> > > We just set up a Ceph cluster, running the latest stable release > >> Ceph > >> >>> > > v12.2.0 (Luminous): > >> >>> > > # ceph --version > >> >>> > > ceph version 12.2.0 (32ce2a3ae5239ee33d6150705cdb24d43bab910c) > >> >>> > > luminous > >> >>> > > (rc) > >> >>> > > > >> >>> > > The goal is to serve Ceph filesystem, for which we created 3 > >> pools: > >> >>> > > # ceph osd lspools > >> >>> > > 1 cephfs_data,2 cephfs_metadata,3 cephfs_cache, > >> >>> > > where > >> >>> > > * cephfs_data is the data pool (36 OSDs on HDDs), which is > >> >>> > > erased-coded; > >> >>> > > * cephfs_metadata is the metadata pool > >> >>> > > * cephfs_cache is the cache tier (3 OSDs on NVMes) for > >> cephfs_data. > >> >>> > > The > >> >>> > > cache-mode is writeback. > >> >>> > > > >> >>> > > Everything had worked fine, until today when we tried to copy a > >> 1.3TB > >> >>> > > file > >> >>> > > to the CephFS. We got the "No space left on device" error! > >> >>> > > > >> >>> > > 'ceph -s' says some OSDs are full: > >> >>> > > # ceph -s > >> >>> > > cluster: > >> >>> > > id: e18516bf-39cb-4670-9f13-88ccb7d19769 > >> >>> > > health: HEALTH_ERR > >> >>> > > full flag(s) set > >> >>> > > 1 full osd(s) > >> >>> > > 1 pools have many more objects per pg than average > >> >>> > > > >> >>> > > services: > >> >>> > > mon: 3 daemons, quorum pulpo-admin,pulpo-mon01,pulpo-mds01 > >> >>> > > mgr: pulpo-mds01(active), standbys: pulpo-admin, pulpo-mon01 > >> >>> > > mds: pulpos-1/1/1 up {0=pulpo-mds01=up:active} > >> >>> > > osd: 39 osds: 39 up, 39 in > >> >>> > > flags full > >> >>> > > > >> >>> > > data: > >> >>> > > pools: 3 pools, 2176 pgs > >> >>> > > objects: 347k objects, 1381 GB > >> >>> > > usage: 2847 GB used, 262 TB / 265 TB avail > >> >>> > > pgs: 2176 active+clean > >> >>> > > > >> >>> > > io: > >> >>> > > client: 19301 kB/s rd, 2935 op/s rd, 0 op/s wr > >> >>> > > > >> >>> > > And indeed the cache pool is full: > >> >>> > > # rados df > >> >>> > > POOL_NAME USED OBJECTS CLONES COPIES MISSING_ON_PRIMARY > >> >>> > > UNFOUND > >> >>> > > DEGRADED RD_OPS RD > >> >>> > > WR_OPS WR > >> >>> > > cephfs_cache 1381G 355385 0 710770 0 > >> >>> > > 0 > >> >>> > > 0 10004954 15 > >> >>> > > 22G 1398063 1611G > >> >>> > > cephfs_data 0 0 0 0 0 > >> >>> > > 0 > >> >>> > > 0 0 > >> >>> > > 0 0 0 > >> >>> > > cephfs_metadata 8515k 24 0 72 0 > >> >>> > > 0 > >> >>> > > 0 3 3 > >> >>> > > 072 3953 10541k > >> >>> > > > >> >>> > > total_objects 355409 > >> >>> > > total_used 2847G > >> >>> > > total_avail 262T > >> >>> > > total_space 265T > >> >>> > > > >> >>> > > However, the data pool is completely empty! So it seems that data > >> has > >> >>> > > only > >> >>> > > been written to the cache pool, but not written back to the data > >> >>> > > pool. > >> >>> > > > >> >>> > > I am really at a loss whether this is due to a setup error on my > >> >>> > > part, or > >> >>> > > a Luminous bug. Could anyone shed some light on this? Please let > >> me > >> >>> > > know if > >> >>> > > you need any further info. > >> >>> > > > >> >>> > > Best, > >> >>> > > Shaw > >> >>> > > _______________________________________________ > >> >>> > > ceph-users mailing list > >> >>> > > ceph-users@xxxxxxxxxxxxxx > >> >>> > > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > >> >>> > > > >> >>> > >> >>> > >> >>> -- > >> >>> Christian Balzer Network/Systems Engineer > >> >>> chibi@xxxxxxx Rakuten Communications > >> >>> _______________________________________________ > >> >>> ceph-users mailing list > >> >>> ceph-users@xxxxxxxxxxxxxx > >> >>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > >> >> > >> >> > >> >> _______________________________________________ > >> >> ceph-users mailing list > >> >> ceph-users@xxxxxxxxxxxxxx > >> >> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > >> >> > >> > > >> > > >> > _______________________________________________ > >> > ceph-users mailing list > >> > ceph-users@xxxxxxxxxxxxxx > >> > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > >> > > >> > > > > -- Christian Balzer Network/Systems Engineer chibi@xxxxxxx Rakuten Communications _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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