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 > _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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