Problem balancing disk space

[Alphe Salas]

Hello,
for some reasons the balancing of disk space use on OSD is not properly
working. Can you please give me hint to solve that issue?

it is supposed that the proper difference betwin min and max osd disk
space use, should be around 20%.

Actually I see that it is more that 40%

follow you will find the list of disk and real use

osd10: Filesystem Size Used Avail Use% Mounted on
osd10: /dev/sda1 1.8T 1.1T 646G 63% /var/lib/ceph/osd/ceph-18
osd10: Filesystem Size Used Avail Use% Mounted on
osd10: /dev/sdb1 1.8T 1.6T 109G 94% /var/lib/ceph/osd/ceph-19
osd09: Filesystem Size Used Avail Use% Mounted on
osd09: /dev/sda1 1.8T 1.5T 216G 88% /var/lib/ceph/osd/ceph-16
osd09: Filesystem Size Used Avail Use% Mounted on
osd09: /dev/sdb1 1.8T 895G 842G 52% /var/lib/ceph/osd/ceph-17
osd08: Filesystem Size Used Avail Use% Mounted on
osd08: /dev/sda1 1.8T 1.6T 153G 92% /var/lib/ceph/osd/ceph-10
osd08: Filesystem Size Used Avail Use% Mounted on
osd08: /dev/sdb1 1.8T 1.7T 84G 96% /var/lib/ceph/osd/ceph-11
osd07: Filesystem Size Used Avail Use% Mounted on
osd07: /dev/sda1 1.8T 1.5T 297G 83% /var/lib/ceph/osd/ceph-14
osd07: Filesystem Size Used Avail Use% Mounted on
osd07: /dev/sdb1 1.8T 1.5T 268G 85% /var/lib/ceph/osd/ceph-15
osd06: Filesystem Size Used Avail Use% Mounted on
osd06: /dev/sda1 1.8T 1.6T 193G 89% /var/lib/ceph/osd/ceph-12
osd06: Filesystem Size Used Avail Use% Mounted on
osd06: /dev/sdb1 1.8T 1.4T 305G 83% /var/lib/ceph/osd/ceph-13
osd05: Filesystem Size Used Avail Use% Mounted on
osd05: /dev/sda1 1.8T 1.3T 434G 76% /var/lib/ceph/osd/ceph-8
osd05: Filesystem Size Used Avail Use% Mounted on
osd05: /dev/sdb1 1.8T 1.2T 526G 70% /var/lib/ceph/osd/ceph-9
osd04: Filesystem Size Used Avail Use% Mounted on
osd04: /dev/sda1 1.8T 1.6T 169G 91% /var/lib/ceph/osd/ceph-6
osd04: Filesystem Size Used Avail Use% Mounted on
osd04: /dev/sdb1 1.8T 1.4T 313G 82% /var/lib/ceph/osd/ceph-7
osd03: Filesystem Size Used Avail Use% Mounted on
osd03: /dev/sda1 1.8T 1.6T 195G 89% /var/lib/ceph/osd/ceph-4
osd03: Filesystem Size Used Avail Use% Mounted on
osd03: /dev/sdb1 1.8T 1.3T 425G 76% /var/lib/ceph/osd/ceph-5
osd02: Filesystem Size Used Avail Use% Mounted on
osd02: /dev/sda1 1.8T 1.4T 362G 80% /var/lib/ceph/osd/ceph-2
osd02: Filesystem Size Used Avail Use% Mounted on
osd02: /dev/sdb1 1.8T 1.5T 211G 88% /var/lib/ceph/osd/ceph-3
osd01: Filesystem Size Used Avail Use% Mounted on
osd01: /dev/sda1 1.8T 1.4T 304G 83% /var/lib/ceph/osd/ceph-0
osd01: Filesystem Size Used Avail Use% Mounted on
osd01: /dev/sdb1 1.8T 1.3T 456G 74% /var/lib/ceph/osd/ceph-1

ceph health detail gives an inacurate estimation of the problem (the
percentages are wrong..)

ceph health detail
HEALTH_WARN 4 near full osd(s)
osd.6 is near full at 85% (real 91%)
osd.10 is near full at 86% (real 92%)
osd.11 is near full at 90% (real 96%)
osd.19 is near full at 88% (real 94%)


Then as you can see on the above disk space use dump I get a usage span
from 52% to 96%.

The question is how can I force the re balancing. I tryed with ceph osd
reweight-by-use 108 and still there is this amazing gap.

actual osd tree is

# id weight type name up/down reweight
-1 35.8 root default
-2 3.58 host osd01
0 1.79 osd.0 up 1
1 1.79 osd.1 up 0.808
-3 3.58 host osd02
2 1.79 osd.2 up 0.9193
3 1.79 osd.3 up 1
-4 3.58 host osd03
4 1.79 osd.4 up 1
5 1.79 osd.5 up 1
-5 3.58 host osd04
6 1.79 osd.6 up 1
7 1.79 osd.7 up 1
-6 3.58 host osd05
8 1.79 osd.8 up 0.7892
9 1.79 osd.9 up 0.7458
-7 3.58 host osd08
10 1.79 osd.10 up 1
11 1.79 osd.11 up 1
-8 3.58 host osd06
12 1.79 osd.12 up 1
13 1.79 osd.13 up 1
-9 3.58 host osd07
14 1.79 osd.14 up 1
15 1.79 osd.15 up 1
-10 3.58 host osd09
16 1.79 osd.16 up 1
17 1.79 osd.17 up 1
-11 3.58 host osd10
18 1.79 osd.18 up 1
19 1.79 osd.19 up 1

Regards,

[Dong Yuan]

Data balancing is depended on the following items:

1. osd counts, more is better, while 20 may be not enough.
2. PG counts, more is better. you can try to create a new pool with
more PGs than default.
3. Object size, little is better. More objects with little size is
better than less objects with big size.
4. Bucket type in the CrushMap. different bucket type means different
balance algorithm.
5. Maybe other issues.

You can use pg dump command to get details about object counts for
each PG, this may be helpful to locate your problem.

Post by Alphe Salas
Hello,
for some reasons the balancing of disk space use on OSD is not properly
working. Can you please give me hint to solve that issue?
it is supposed that the proper difference betwin min and max osd disk space
use, should be around 20%.
Actually I see that it is more that 40%
follow you will find the list of disk and real use
osd10: Filesystem Size Used Avail Use% Mounted on
osd10: /dev/sda1 1.8T 1.1T 646G 63% /var/lib/ceph/osd/ceph-18
osd10: Filesystem Size Used Avail Use% Mounted on
osd10: /dev/sdb1 1.8T 1.6T 109G 94% /var/lib/ceph/osd/ceph-19
osd09: Filesystem Size Used Avail Use% Mounted on
osd09: /dev/sda1 1.8T 1.5T 216G 88% /var/lib/ceph/osd/ceph-16
osd09: Filesystem Size Used Avail Use% Mounted on
osd09: /dev/sdb1 1.8T 895G 842G 52% /var/lib/ceph/osd/ceph-17
osd08: Filesystem Size Used Avail Use% Mounted on
osd08: /dev/sda1 1.8T 1.6T 153G 92% /var/lib/ceph/osd/ceph-10
osd08: Filesystem Size Used Avail Use% Mounted on
osd08: /dev/sdb1 1.8T 1.7T 84G 96% /var/lib/ceph/osd/ceph-11
osd07: Filesystem Size Used Avail Use% Mounted on
osd07: /dev/sda1 1.8T 1.5T 297G 83% /var/lib/ceph/osd/ceph-14
osd07: Filesystem Size Used Avail Use% Mounted on
osd07: /dev/sdb1 1.8T 1.5T 268G 85% /var/lib/ceph/osd/ceph-15
osd06: Filesystem Size Used Avail Use% Mounted on
osd06: /dev/sda1 1.8T 1.6T 193G 89% /var/lib/ceph/osd/ceph-12
osd06: Filesystem Size Used Avail Use% Mounted on
osd06: /dev/sdb1 1.8T 1.4T 305G 83% /var/lib/ceph/osd/ceph-13
osd05: Filesystem Size Used Avail Use% Mounted on
osd05: /dev/sda1 1.8T 1.3T 434G 76% /var/lib/ceph/osd/ceph-8
osd05: Filesystem Size Used Avail Use% Mounted on
osd05: /dev/sdb1 1.8T 1.2T 526G 70% /var/lib/ceph/osd/ceph-9
osd04: Filesystem Size Used Avail Use% Mounted on
osd04: /dev/sda1 1.8T 1.6T 169G 91% /var/lib/ceph/osd/ceph-6
osd04: Filesystem Size Used Avail Use% Mounted on
osd04: /dev/sdb1 1.8T 1.4T 313G 82% /var/lib/ceph/osd/ceph-7
osd03: Filesystem Size Used Avail Use% Mounted on
osd03: /dev/sda1 1.8T 1.6T 195G 89% /var/lib/ceph/osd/ceph-4
osd03: Filesystem Size Used Avail Use% Mounted on
osd03: /dev/sdb1 1.8T 1.3T 425G 76% /var/lib/ceph/osd/ceph-5
osd02: Filesystem Size Used Avail Use% Mounted on
osd02: /dev/sda1 1.8T 1.4T 362G 80% /var/lib/ceph/osd/ceph-2
osd02: Filesystem Size Used Avail Use% Mounted on
osd02: /dev/sdb1 1.8T 1.5T 211G 88% /var/lib/ceph/osd/ceph-3
osd01: Filesystem Size Used Avail Use% Mounted on
osd01: /dev/sda1 1.8T 1.4T 304G 83% /var/lib/ceph/osd/ceph-0
osd01: Filesystem Size Used Avail Use% Mounted on
osd01: /dev/sdb1 1.8T 1.3T 456G 74% /var/lib/ceph/osd/ceph-1
ceph health detail gives an inacurate estimation of the problem (the
percentages are wrong..)
ceph health detail
HEALTH_WARN 4 near full osd(s)
osd.6 is near full at 85% (real 91%)
osd.10 is near full at 86% (real 92%)
osd.11 is near full at 90% (real 96%)
osd.19 is near full at 88% (real 94%)
Then as you can see on the above disk space use dump I get a usage span from
52% to 96%.
The question is how can I force the re balancing. I tryed with ceph osd
reweight-by-use 108 and still there is this amazing gap.
actual osd tree is
# id weight type name up/down reweight
-1 35.8 root default
-2 3.58 host osd01
0 1.79 osd.0 up 1
1 1.79 osd.1 up 0.808
-3 3.58 host osd02
2 1.79 osd.2 up 0.9193
3 1.79 osd.3 up 1
-4 3.58 host osd03
4 1.79 osd.4 up 1
5 1.79 osd.5 up 1
-5 3.58 host osd04
6 1.79 osd.6 up 1
7 1.79 osd.7 up 1
-6 3.58 host osd05
8 1.79 osd.8 up 0.7892
9 1.79 osd.9 up 0.7458
-7 3.58 host osd08
10 1.79 osd.10 up 1
11 1.79 osd.11 up 1
-8 3.58 host osd06
12 1.79 osd.12 up 1
13 1.79 osd.13 up 1
-9 3.58 host osd07
14 1.79 osd.14 up 1
15 1.79 osd.15 up 1
-10 3.58 host osd09
16 1.79 osd.16 up 1
17 1.79 osd.17 up 1
-11 3.58 host osd10
18 1.79 osd.18 up 1
19 1.79 osd.19 up 1
Regards,
--
Alphe Salas
I.T ingeneer
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[huang jun]

maybe you can reset the pg numbers
the recommend number is
pg = (100 * osds) / pool replicas
and ceph prefers 2^N.
for example:
a cluster have 20 OSDs and use default data pool with 2 replicas,
then
pg = (20 * 100 )/2 = 1000, so you can set pg of data pool to 1024.
$ ceph osd pool set data pg_num 640 (bc ceph limit to 32*osds)
and then set it to 1024
$ ceph osd pool set data pg_num 640

finally, set pgp_num fragile osd backfill,
$ ceph osd pool set data pgp_num 1024

Post by Dong Yuan
1. osd counts, more is better, while 20 may be not enough.
2. PG counts, more is better. you can try to create a new pool with
more PGs than default.
3. Object size, little is better. More objects with little size is
better than less objects with big size.
4. Bucket type in the CrushMap. different bucket type means different
balance algorithm.
5. Maybe other issues.
You can use pg dump command to get details about object counts for
each PG, this may be helpful to locate your problem.

Post by Alphe Salas
Hello,
for some reasons the balancing of disk space use on OSD is not properly
working. Can you please give me hint to solve that issue?
it is supposed that the proper difference betwin min and max osd disk space
use, should be around 20%.
Actually I see that it is more that 40%
follow you will find the list of disk and real use
osd10: Filesystem Size Used Avail Use% Mounted on
osd10: /dev/sda1 1.8T 1.1T 646G 63% /var/lib/ceph/osd/ceph-18
osd10: Filesystem Size Used Avail Use% Mounted on
osd10: /dev/sdb1 1.8T 1.6T 109G 94% /var/lib/ceph/osd/ceph-19
osd09: Filesystem Size Used Avail Use% Mounted on
osd09: /dev/sda1 1.8T 1.5T 216G 88% /var/lib/ceph/osd/ceph-16
osd09: Filesystem Size Used Avail Use% Mounted on
osd09: /dev/sdb1 1.8T 895G 842G 52% /var/lib/ceph/osd/ceph-17
osd08: Filesystem Size Used Avail Use% Mounted on
osd08: /dev/sda1 1.8T 1.6T 153G 92% /var/lib/ceph/osd/ceph-10
osd08: Filesystem Size Used Avail Use% Mounted on
osd08: /dev/sdb1 1.8T 1.7T 84G 96% /var/lib/ceph/osd/ceph-11
osd07: Filesystem Size Used Avail Use% Mounted on
osd07: /dev/sda1 1.8T 1.5T 297G 83% /var/lib/ceph/osd/ceph-14
osd07: Filesystem Size Used Avail Use% Mounted on
osd07: /dev/sdb1 1.8T 1.5T 268G 85% /var/lib/ceph/osd/ceph-15
osd06: Filesystem Size Used Avail Use% Mounted on
osd06: /dev/sda1 1.8T 1.6T 193G 89% /var/lib/ceph/osd/ceph-12
osd06: Filesystem Size Used Avail Use% Mounted on
osd06: /dev/sdb1 1.8T 1.4T 305G 83% /var/lib/ceph/osd/ceph-13
osd05: Filesystem Size Used Avail Use% Mounted on
osd05: /dev/sda1 1.8T 1.3T 434G 76% /var/lib/ceph/osd/ceph-8
osd05: Filesystem Size Used Avail Use% Mounted on
osd05: /dev/sdb1 1.8T 1.2T 526G 70% /var/lib/ceph/osd/ceph-9
osd04: Filesystem Size Used Avail Use% Mounted on
osd04: /dev/sda1 1.8T 1.6T 169G 91% /var/lib/ceph/osd/ceph-6
osd04: Filesystem Size Used Avail Use% Mounted on
osd04: /dev/sdb1 1.8T 1.4T 313G 82% /var/lib/ceph/osd/ceph-7
osd03: Filesystem Size Used Avail Use% Mounted on
osd03: /dev/sda1 1.8T 1.6T 195G 89% /var/lib/ceph/osd/ceph-4
osd03: Filesystem Size Used Avail Use% Mounted on
osd03: /dev/sdb1 1.8T 1.3T 425G 76% /var/lib/ceph/osd/ceph-5
osd02: Filesystem Size Used Avail Use% Mounted on
osd02: /dev/sda1 1.8T 1.4T 362G 80% /var/lib/ceph/osd/ceph-2
osd02: Filesystem Size Used Avail Use% Mounted on
osd02: /dev/sdb1 1.8T 1.5T 211G 88% /var/lib/ceph/osd/ceph-3
osd01: Filesystem Size Used Avail Use% Mounted on
osd01: /dev/sda1 1.8T 1.4T 304G 83% /var/lib/ceph/osd/ceph-0
osd01: Filesystem Size Used Avail Use% Mounted on
osd01: /dev/sdb1 1.8T 1.3T 456G 74% /var/lib/ceph/osd/ceph-1
ceph health detail gives an inacurate estimation of the problem (the
percentages are wrong..)
ceph health detail
HEALTH_WARN 4 near full osd(s)
osd.6 is near full at 85% (real 91%)
osd.10 is near full at 86% (real 92%)
osd.11 is near full at 90% (real 96%)
osd.19 is near full at 88% (real 94%)
Then as you can see on the above disk space use dump I get a usage span from
52% to 96%.
The question is how can I force the re balancing. I tryed with ceph osd
reweight-by-use 108 and still there is this amazing gap.
actual osd tree is
# id weight type name up/down reweight
-1 35.8 root default
-2 3.58 host osd01
0 1.79 osd.0 up 1
1 1.79 osd.1 up 0.808
-3 3.58 host osd02
2 1.79 osd.2 up 0.9193
3 1.79 osd.3 up 1
-4 3.58 host osd03
4 1.79 osd.4 up 1
5 1.79 osd.5 up 1
-5 3.58 host osd04
6 1.79 osd.6 up 1
7 1.79 osd.7 up 1
-6 3.58 host osd05
8 1.79 osd.8 up 0.7892
9 1.79 osd.9 up 0.7458
-7 3.58 host osd08
10 1.79 osd.10 up 1
11 1.79 osd.11 up 1
-8 3.58 host osd06
12 1.79 osd.12 up 1
13 1.79 osd.13 up 1
-9 3.58 host osd07
14 1.79 osd.14 up 1
15 1.79 osd.15 up 1
-10 3.58 host osd09
16 1.79 osd.16 up 1
17 1.79 osd.17 up 1
-11 3.58 host osd10
18 1.79 osd.18 up 1
19 1.79 osd.19 up 1
Regards,
--
Alphe Salas
I.T ingeneer
--
To unsubscribe from this list: send the line "unsubscribe ceph-devel" in
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--
Dong Yuan
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