Hi Anthony
CEPH OSD DF TREE :: ===========================
ID CLASS WEIGHT REWEIGHT SIZE RAW USE DATA OMAP
META AVAIL %USE VAR PGS STATUS TYPE NAME
-51 12.22272 - 12 TiB 4.8 TiB 4.8 TiB 112 MiB
20 GiB 7.4 TiB 39.21 3.24 - root cache_root
-27 0.87329 - 894 GiB 306 GiB 305 GiB 8.1 MiB
1.3 GiB 588 GiB 34.25 2.83 - host cache_node1
0 ssd 0.87329 1.00000 894 GiB 306 GiB 305 GiB 8.1 MiB
1.3 GiB 588 GiB 34.25 2.83 4 up osd.0
-45 0.87299 - 894 GiB 382 GiB 381 GiB 6.3 MiB
1.5 GiB 512 GiB 42.76 3.53 - host cache_node10
45 ssd 0.87299 1.00000 894 GiB 382 GiB 381 GiB 6.3 MiB
1.5 GiB 512 GiB 42.76 3.53 3 up osd.45
-47 0.87299 - 894 GiB 458 GiB 456 GiB 4.1 MiB
1.7 GiB 436 GiB 51.21 4.23 - host cache_node11
50 ssd 0.87299 1.00000 894 GiB 458 GiB 456 GiB 4.1 MiB
1.7 GiB 436 GiB 51.21 4.23 6 up osd.50
-49 0.87299 - 894 GiB 535 GiB 533 GiB 8.0 MiB
1.7 GiB 359 GiB 59.84 4.94 - host cache_node12
55 ssd 0.87299 1.00000 894 GiB 535 GiB 533 GiB 8.0 MiB
1.7 GiB 359 GiB 59.84 4.94 7 up osd.55
-53 0.87329 - 894 GiB 230 GiB 229 GiB 10 MiB
1.2 GiB 664 GiB 25.75 2.13 - host cache_node13
60 ssd 0.87329 1.00000 894 GiB 230 GiB 229 GiB 10 MiB
1.2 GiB 664 GiB 25.75 2.13 3 up osd.60
-59 0.87329 - 894 GiB 231 GiB 230 GiB 11 MiB
1.2 GiB 663 GiB 25.80 2.13 - host cache_node14
65 ssd 0.87329 1.00000 894 GiB 231 GiB 230 GiB 11 MiB
1.2 GiB 663 GiB 25.80 2.13 3 up osd.65
-29 0.87299 - 894 GiB 386 GiB 384 GiB 4.0 MiB
1.7 GiB 509 GiB 43.13 3.56 - host cache_node2
5 ssd 0.87299 1.00000 894 GiB 386 GiB 384 GiB 4.0 MiB
1.7 GiB 509 GiB 43.13 3.56 4 up osd.5
-31 0.87299 - 894 GiB 154 GiB 153 GiB 3.0 MiB
1.0 GiB 740 GiB 17.26 1.42 - host cache_node3
10 ssd 0.87299 1.00000 894 GiB 154 GiB 153 GiB 3.0 MiB
1.0 GiB 740 GiB 17.26 1.42 2 up osd.10
-33 0.87299 - 894 GiB 308 GiB 307 GiB 8.8 MiB
1.4 GiB 586 GiB 34.49 2.85 - host cache_node4
15 ssd 0.87299 1.00000 894 GiB 308 GiB 307 GiB 8.8 MiB
1.4 GiB 586 GiB 34.49 2.85 4 up osd.15
-35 0.87299 - 894 GiB 383 GiB 381 GiB 10 MiB
1.5 GiB 512 GiB 42.79 3.53 - host cache_node5
20 ssd 0.87299 1.00000 894 GiB 383 GiB 381 GiB 10 MiB
1.5 GiB 512 GiB 42.79 3.53 4 up osd.20
-37 0.87299 - 894 GiB 156 GiB 155 GiB 3.2 MiB
1.4 GiB 738 GiB 17.48 1.44 - host cache_node6
25 ssd 0.87299 1.00000 894 GiB 156 GiB 155 GiB 3.2 MiB
1.4 GiB 738 GiB 17.48 1.44 2 up osd.25
-39 0.87299 - 894 GiB 611 GiB 609 GiB 13 MiB
1.9 GiB 284 GiB 68.28 5.64 - host cache_node7
30 ssd 0.87299 1.00000 894 GiB 611 GiB 609 GiB 13 MiB
1.9 GiB 284 GiB 68.28 5.64 8 up osd.30
-41 0.87299 - 894 GiB 156 GiB 155 GiB 13 MiB
1.1 GiB 738 GiB 17.50 1.44 - host cache_node8
35 ssd 0.87299 1.00000 894 GiB 156 GiB 155 GiB 13 MiB
1.1 GiB 738 GiB 17.50 1.44 2 up osd.35
-43 0.87299 - 894 GiB 612 GiB 610 GiB 9.7 MiB
1.8 GiB 282 GiB 68.46 5.65 - host cache_node9
40 ssd 0.87299 1.00000 894 GiB 612 GiB 610 GiB 9.7 MiB
1.8 GiB 282 GiB 68.46 5.65 8 up osd.40
-1 195.60869 - 196 TiB 20 TiB 20 TiB 810 MiB
77 GiB 175 TiB 10.42 0.86 - root default
-3 13.97198 - 14 TiB 1.3 TiB 1.3 TiB 31 MiB
5.1 GiB 13 TiB 9.07 0.75 - host node1
1 ssd 3.49300 1.00000 3.5 TiB 309 GiB 308 GiB 7.8 MiB
1.2 GiB 3.2 TiB 8.64 0.71 36 up osd.1
2 ssd 3.49300 1.00000 3.5 TiB 331 GiB 330 GiB 5.2 MiB
1.4 GiB 3.2 TiB 9.26 0.76 36 up osd.2
3 ssd 3.49300 1.00000 3.5 TiB 292 GiB 291 GiB 8.2 MiB
1.2 GiB 3.2 TiB 8.16 0.67 34 up osd.3
4 ssd 3.49300 1.00000 3.5 TiB 365 GiB 364 GiB 9.9 MiB
1.4 GiB 3.1 TiB 10.21 0.84 38 up osd.4
-21 13.97200 - 14 TiB 1.5 TiB 1.5 TiB 24 MiB
5.8 GiB 12 TiB 10.73 0.89 - host node10
46 ssd 3.49300 1.00000 3.5 TiB 332 GiB 331 GiB 3.4 MiB
1.2 GiB 3.2 TiB 9.28 0.77 37 up osd.46
47 ssd 3.49300 1.00000 3.5 TiB 368 GiB 366 GiB 8.7 MiB
1.6 GiB 3.1 TiB 10.29 0.85 38 up osd.47
48 ssd 3.49300 1.00000 3.5 TiB 459 GiB 457 GiB 5.1 MiB
1.7 GiB 3.0 TiB 12.84 1.06 42 up osd.48
49 ssd 3.49300 1.00000 3.5 TiB 376 GiB 374 GiB 6.4 MiB
1.3 GiB 3.1 TiB 10.50 0.87 39 up osd.49
-23 13.97200 - 14 TiB 1.6 TiB 1.6 TiB 30 MiB
5.4 GiB 12 TiB 11.23 0.93 - host node11
51 ssd 3.49300 1.00000 3.5 TiB 426 GiB 424 GiB 6.1 MiB
1.3 GiB 3.1 TiB 11.90 0.98 40 up osd.51
52 ssd 3.49300 1.00000 3.5 TiB 482 GiB 481 GiB 9.2 MiB
1.4 GiB 3.0 TiB 13.48 1.11 44 up osd.52
53 ssd 3.49300 1.00000 3.5 TiB 330 GiB 329 GiB 4.2 MiB
1.2 GiB 3.2 TiB 9.23 0.76 36 up osd.53
54 ssd 3.49300 1.00000 3.5 TiB 369 GiB 368 GiB 10 MiB
1.4 GiB 3.1 TiB 10.32 0.85 40 up osd.54
-25 13.97200 - 14 TiB 1.6 TiB 1.6 TiB 234 MiB
5.5 GiB 12 TiB 11.30 0.93 - host node12
56 ssd 3.49300 1.00000 3.5 TiB 348 GiB 346 GiB 4.7 MiB
1.5 GiB 3.2 TiB 9.72 0.80 36 up osd.56
57 ssd 3.49300 1.00000 3.5 TiB 473 GiB 471 GiB 218 MiB
1.4 GiB 3.0 TiB 13.22 1.09 42 up osd.57
58 ssd 3.49300 1.00000 3.5 TiB 348 GiB 347 GiB 5.4 MiB
1.2 GiB 3.2 TiB 9.74 0.80 38 up osd.58
59 ssd 3.49300 1.00000 3.5 TiB 448 GiB 447 GiB 5.2 MiB
1.4 GiB 3.1 TiB 12.54 1.03 42 up osd.59
-55 13.97235 - 14 TiB 1.5 TiB 1.5 TiB 26 MiB
5.5 GiB 12 TiB 10.73 0.89 - host node13
61 ssd 3.49309 1.00000 3.5 TiB 382 GiB 381 GiB 8 MiB
1.3 GiB 3.1 TiB 10.69 0.88 39 up osd.61
62 ssd 3.49309 1.00000 3.5 TiB 338 GiB 337 GiB 6.5 MiB
1.4 GiB 3.2 TiB 9.46 0.78 37 up osd.62
63 ssd 3.49309 1.00000 3.5 TiB 444 GiB 442 GiB 5.6 MiB
1.4 GiB 3.1 TiB 12.40 1.02 41 up osd.63
64 ssd 3.49309 1.00000 3.5 TiB 372 GiB 370 GiB 6.1 MiB
1.4 GiB 3.1 TiB 10.39 0.86 40 up osd.64
-57 13.97235 - 14 TiB 1.5 TiB 1.5 TiB 34 MiB
5.5 GiB 12 TiB 10.56 0.87 - host node14
66 ssd 3.49309 1.00000 3.5 TiB 387 GiB 385 GiB 9.1 MiB
1.3 GiB 3.1 TiB 10.81 0.89 38 up osd.66
67 ssd 3.49309 1.00000 3.5 TiB 350 GiB 349 GiB 7.3 MiB
1.4 GiB 3.2 TiB 9.79 0.81 38 up osd.67
68 ssd 3.49309 1.00000 3.5 TiB 444 GiB 443 GiB 7.2 MiB
1.5 GiB 3.1 TiB 12.41 1.03 43 up osd.68
69 ssd 3.49309 1.00000 3.5 TiB 330 GiB 329 GiB 11 MiB
1.3 GiB 3.2 TiB 9.23 0.76 36 up osd.69
-5 13.97200 - 14 TiB 1.5 TiB 1.5 TiB 242 MiB
5.8 GiB 13 TiB 10.43 0.86 - host node2
6 ssd 3.49300 1.00000 3.5 TiB 430 GiB 428 GiB 6.8 MiB
1.7 GiB 3.1 TiB 12.01 0.99 42 up osd.6
7 ssd 3.49300 1.00000 3.5 TiB 309 GiB 308 GiB 6.9 MiB
1.5 GiB 3.2 TiB 8.65 0.71 36 up osd.7
8 ssd 3.49300 1.00000 3.5 TiB 392 GiB 391 GiB 217 MiB
1.3 GiB 3.1 TiB 10.96 0.91 42 up osd.8
9 ssd 3.49300 1.00000 3.5 TiB 361 GiB 360 GiB 11 MiB
1.3 GiB 3.1 TiB 10.10 0.83 38 up osd.9
-7 13.97200 - 14 TiB 1.4 TiB 1.4 TiB 28 MiB
5.6 GiB 13 TiB 10.00 0.83 - host node3
11 ssd 3.49300 1.00000 3.5 TiB 377 GiB 375 GiB 10 MiB
1.6 GiB 3.1 TiB 10.54 0.87 40 up osd.11
12 ssd 3.49300 1.00000 3.5 TiB 347 GiB 346 GiB 6.1 MiB
1.4 GiB 3.2 TiB 9.70 0.80 39 up osd.12
13 ssd 3.49300 1.00000 3.5 TiB 393 GiB 392 GiB 5.8 MiB
1.4 GiB 3.1 TiB 10.99 0.91 41 up osd.13
14 ssd 3.49300 1.00000 3.5 TiB 313 GiB 312 GiB 5.7 MiB
1.3 GiB 3.2 TiB 8.76 0.72 35 up osd.14
-9 13.97200 - 14 TiB 1.5 TiB 1.5 TiB 31 MiB
5.2 GiB 12 TiB 10.64 0.88 - host node4
16 ssd 3.49300 1.00000 3.5 TiB 371 GiB 369 GiB 5.2 MiB
1.4 GiB 3.1 TiB 10.36 0.86 39 up osd.16
17 ssd 3.49300 1.00000 3.5 TiB 371 GiB 370 GiB 10 MiB
1.3 GiB 3.1 TiB 10.38 0.86 39 up osd.17
18 ssd 3.49300 1.00000 3.5 TiB 313 GiB 312 GiB 7.7 MiB
1.2 GiB 3.2 TiB 8.75 0.72 35 up osd.18
19 ssd 3.49300 1.00000 3.5 TiB 467 GiB 466 GiB 7.7 MiB
1.3 GiB 3.0 TiB 13.06 1.08 44 up osd.19
-11 13.97200 - 14 TiB 1.7 TiB 1.7 TiB 28 MiB
5.7 GiB 12 TiB 11.90 0.98 - host node5
21 ssd 3.49300 1.00000 3.5 TiB 462 GiB 460 GiB 4.1 MiB
1.6 GiB 3.0 TiB 12.91 1.07 44 up osd.21
22 ssd 3.49300 1.00000 3.5 TiB 444 GiB 442 GiB 8.2 MiB
1.4 GiB 3.1 TiB 12.41 1.02 42 up osd.22
23 ssd 3.49300 1.00000 3.5 TiB 399 GiB 398 GiB 8.2 MiB
1.4 GiB 3.1 TiB 11.15 0.92 40 up osd.23
24 ssd 3.49300 1.00000 3.5 TiB 399 GiB 397 GiB 7.8 MiB
1.3 GiB 3.1 TiB 11.15 0.92 41 up osd.24
-13 13.97200 - 14 TiB 1.4 TiB 1.4 TiB 28 MiB
5.6 GiB 13 TiB 10.31 0.85 - host node6
26 ssd 3.49300 1.00000 3.5 TiB 361 GiB 359 GiB 5.9 MiB
1.3 GiB 3.1 TiB 10.08 0.83 38 up osd.26
27 ssd 3.49300 1.00000 3.5 TiB 391 GiB 390 GiB 10 MiB
1.3 GiB 3.1 TiB 10.93 0.90 40 up osd.27
28 ssd 3.49300 1.00000 3.5 TiB 393 GiB 391 GiB 5.4 MiB
1.6 GiB 3.1 TiB 10.97 0.91 40 up osd.28
29 ssd 3.49300 1.00000 3.5 TiB 331 GiB 330 GiB 6.5 MiB
1.4 GiB 3.2 TiB 9.26 0.76 37 up osd.29
-15 13.97200 - 14 TiB 1.3 TiB 1.3 TiB 23 MiB
5.6 GiB 13 TiB 9.29 0.77 - host node7
31 ssd 3.49300 1.00000 3.5 TiB 326 GiB 325 GiB 7.2 MiB
1.4 GiB 3.2 TiB 9.12 0.75 38 up osd.31
32 ssd 3.49300 1.00000 3.5 TiB 329 GiB 327 GiB 5.4 MiB
1.3 GiB 3.2 TiB 9.19 0.76 37 up osd.32
33 ssd 3.49300 1.00000 3.5 TiB 293 GiB 291 GiB 5.8 MiB
1.6 GiB 3.2 TiB 8.18 0.68 34 up osd.33
34 ssd 3.49300 1.00000 3.5 TiB 381 GiB 380 GiB 4.7 MiB
1.4 GiB 3.1 TiB 10.65 0.88 41 up osd.34
-17 13.97200 - 14 TiB 1.4 TiB 1.4 TiB 25 MiB
5.3 GiB 13 TiB 10.25 0.85 - host node8
36 ssd 3.49300 1.00000 3.5 TiB 336 GiB 335 GiB 3.6 MiB
1.3 GiB 3.2 TiB 9.39 0.78 37 up osd.36
37 ssd 3.49300 1.00000 3.5 TiB 397 GiB 396 GiB 7.2 MiB
1.3 GiB 3.1 TiB 11.11 0.92 40 up osd.37
38 ssd 3.49300 1.00000 3.5 TiB 365 GiB 363 GiB 7.9 MiB
1.4 GiB 3.1 TiB 10.20 0.84 40 up osd.38
39 ssd 3.49300 1.00000 3.5 TiB 368 GiB 367 GiB 5.8 MiB
1.3 GiB 3.1 TiB 10.29 0.85 38 up osd.39
-19 13.97200 - 14 TiB 1.3 TiB 1.3 TiB 26 MiB
5.0 GiB 13 TiB 9.41 0.78 - host node9
41 ssd 3.49300 1.00000 3.5 TiB 333 GiB 332 GiB 7.3 MiB
1.3 GiB 3.2 TiB 9.31 0.77 39 up osd.41
42 ssd 3.49300 1.00000 3.5 TiB 346 GiB 345 GiB 6.2 MiB
1.3 GiB 3.2 TiB 9.69 0.80 39 up osd.42
43 ssd 3.49300 1.00000 3.5 TiB 336 GiB 335 GiB 8.4 MiB
1.2 GiB 3.2 TiB 9.40 0.78 37 up osd.43
44 ssd 3.49300 1.00000 3.5 TiB 330 GiB 329 GiB 4.2 MiB
1.2 GiB 3.2 TiB 9.23 0.76 36 up osd.44
TOTAL 208 TiB 25 TiB 25 TiB 922 MiB
97 GiB 183 TiB 12.11
MIN/MAX VAR: 0.67/5.65 STDDEV: 14.49
CEPH DF DETAIL :: =============================
--- RAW STORAGE ---
CLASS SIZE AVAIL USED RAW USED %RAW USED
ssd 208 TiB 183 TiB 25 TiB 25 TiB 12.11
TOTAL 208 TiB 183 TiB 25 TiB 25 TiB 12.11
--- POOLS ---
POOL ID PGS STORED (DATA) (OMAP) OBJECTS
USED (DATA) (OMAP) %USED MAX AVAIL QUOTA OBJECTS QUOTA
BYTES DIRTY USED COMPR UNDER COMPR
device_health_metrics 2 1 214 MiB 0 B 214 MiB 73
429 MiB 0 B 429 MiB 0 80 TiB N/A N/A
N/A 0 B 0 B
volumes 3 1024 8.5 TiB 8.5 TiB 54 MiB 2.37M
17 TiB 17 TiB 108 MiB 9.67 80 TiB N/A N/A
N/A 0 B 0 B
volumes_cache 4 32 2.4 TiB 2.4 TiB 52 MiB 1.09M
4.8 TiB 4.8 TiB 104 MiB 59.54 1.6 TiB N/A N/A
499.25k 0 B 0 B
images 5 32 712 GiB 712 GiB 42 MiB 90.97k
1.4 TiB 1.4 TiB 85 MiB 0.86 80 TiB N/A N/A
N/A 0 B 0 B
internal 6 32 941 GiB 941 GiB 11 MiB 247.76k
1.8 TiB 1.8 TiB 22 MiB 1.14 80 TiB N/A N/A
N/A 0 B 0 B
CEPH OSD POOL LS DETAIL :: ====================
pool 2 'device_health_metrics' replicated size 2 min_size 1 crush_rule
0 object_hash rjenkins pg_num 1 pgp_num 1 autoscale_mode on
last_change 44903 flags hashpspool stripe_width 0 pg_num_min 1
application mgr_devicehealth
pool 3 'volumes' replicated size 2 min_size 1 crush_rule 0 object_hash
rjenkins pg_num 1024 pgp_num 1024 autoscale_mode off last_change 63235
lfor 353/353/62134 flags hashpspool,selfmanaged_snaps tiers 4
read_tier 4 write_tier 4 stripe_width 0 application rbd
pool 4 'volumes_cache' replicated size 2 min_size 1 crush_rule 1
object_hash rjenkins pg_num 32 pgp_num 32 autoscale_mode off
last_change 63235 lfor 353/353/353 flags
hashpspool,incomplete_clones,selfmanaged_snaps tier_of 3 cache_mode
writeback target_bytes 3298534883328 hit_set
bloom{false_positive_probability: 0.05, target_size: 0, seed: 0}
14400s x4 decay_rate 0 search_last_n 0 stripe_width 0 application rbd
pool 5 'images' replicated size 2 min_size 1 crush_rule 0 object_hash
rjenkins pg_num 32 pgp_num 32 autoscale_mode on last_change 51925 lfor
0/0/368 flags hashpspool,selfmanaged_snaps stripe_width 0 application
rbd
pool 6 'internal' replicated size 2 min_size 1 crush_rule 0
object_hash rjenkins pg_num 32 pgp_num 32 autoscale_mode on
last_change 49949 flags hashpspool,selfmanaged_snaps stripe_width 0
application rbd
Thanks and Regards
Vishnu Bhaskar
Acceleron Labs Pvt Ltd
Bangalore, India
On Wed, Aug 13, 2025 at 11:28 PM Anthony D'Atri <anthony.da...@gmail.com>
wrote:
> Ah. Note “average”. These warnings can be a bit alarmist. Please send
>
> `ceph df`
> `ceph osd dump | grep pool`
>
>
>
> > On Aug 13, 2025, at 2:24 AM, Vishnu Bhaskar <vishn...@acceleronlabs.com>
> wrote:
> >
> > Hi,
> > My cluster is showing this warning
> >
> > [WRN] MANY_OBJECTS_PER_PG: 1 pools have many more objects per pg than
> average
> > pool volumes_cache objects per pg (34082) is more than 10.0448
> > times cluster average (3393)
> >
> >
> >
> > Thanks and Regards
> > Vishnu Bhaskar
> > Acceleron Labs Pvt Ltd
> > Bangalore, India
> >
> >
> >> On Wed, Aug 13, 2025 at 1:35 PM Anthony D'Atri <a...@dreamsnake.net>
> wrote:
> >>
> >> Cache tiers are deprecated, I strongly advise finding a way to factor it
> >> out of your deployment.
> >>
> >> There was some discussion of this in the past, e.g.
> >>
> >>
> https://ceph-users.ceph.narkive.com/0LxBSHEQ/changing-pg-num-on-cache-pool
> >>
> >> The PG to RADOS object ratio isn't necessarily in and of itself a
> problem,
> >> as the dynamics of pg_num for a pool depend on the data and the access
> >> modality. When multiple pools share the same OSDs, there are tradeoffs
> >> that include what the pools are for, and how much data each stores. RGW
> >> index pools, for example, need more PGs than their data volume would
> >> otherwise indicate.
> >>
> >> Is your cache pool for sure limited to *only* the SSDs you expect, or
> does
> >> it specify a CRUSH rule that also lands on HDDs?
> >>
> >> -- the former Cepher known as Anthony
> >>
> >> On Aug 13, 2025, at 12:15 AM, Vishnu Bhaskar <
> vishn...@acceleronlabs.com>
> >> wrote:
> >>
> >> Hi Team,
> >>
> >> I have an OpenStack Ceph cluster where the Cinder volumes pool uses a
> cache
> >> pool named *volumes_cache*.
> >>
> >> Due to performance issues, I observed that the cache pool has fewer PGs
> and
> >> a high PG-to-object ratio, approximately 10x higher than normal. For
> >> instance, one PG contains around 35,000 objects. I am planning to
> increase
> >> the PG number for the cache pool.
> >>
> >> For the base pool, I was able to increase the PG count without any
> issues.
> >> However, for the cache pool, I encountered a warning indicating that a
> >> force argument is required. In my lab environment, I found that changing
> >> the cache pool mode to *none* allowed me to modify the PG number.
> >>
> >> Since this is my production setup, I would like to know if there is a
> safe
> >> and recommended procedure to increase the PG number of a *cache pool*
> >> without impacting the environment.
> >>
> >> Kindly advise on the best approach.
> >>
> >> Thanks and Regards
> >> Vishnu Bhaskar
> >> Acceleron Labs Pvt Ltd
> >> Bangalore, India
> >> _______________________________________________
> >> ceph-users mailing list -- ceph-users@ceph.io
> >> To unsubscribe send an email to ceph-users-le...@ceph.io
> >>
> >>
> >>
> > _______________________________________________
> > ceph-users mailing list -- ceph-users@ceph.io
> > To unsubscribe send an email to ceph-users-le...@ceph.io
>
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