ceph:modifying_crush_map
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Table of Contents
Modifying CRUSH map
| Documentation | |
|---|---|
| Name: | Modifying CRUSH map |
| Description: | How to modify CRUSH map |
| Modification date : | 11/06/2019 |
| Owner: | dodger@ciberterminal.net |
| Notify changes to: | Owner |
| Tags: | ceph, object storage |
Information
The described process is a advanced process, take care.
Pre-Requirements
- Knowledge of ceph management
- Understand of CRUSH
- Understand of CRUSH mapping options
Instructions
Review actual CRUSH tree
ceph osd crush tree
Example:
avmlp-osm-001 ~ # ceph osd crush tree ID CLASS WEIGHT TYPE NAME -1 39.97986 root default -3 1.99899 host avmlp-osd-001 0 hdd 1.99899 osd.0 -5 1.99899 host avmlp-osd-002 1 hdd 1.99899 osd.1 -7 1.99899 host avmlp-osd-003 2 hdd 1.99899 osd.2 -9 1.99899 host avmlp-osd-004 3 hdd 1.99899 osd.3 -11 1.99899 host avmlp-osd-005 4 hdd 1.99899 osd.4 -13 1.99899 host avmlp-osd-006 5 hdd 1.99899 osd.5 -15 1.99899 host avmlp-osd-007 6 hdd 1.99899 osd.6 -17 1.99899 host avmlp-osd-008 7 hdd 1.99899 osd.7 -19 1.99899 host avmlp-osd-009 8 hdd 1.99899 osd.8 -21 1.99899 host avmlp-osd-010 9 hdd 1.99899 osd.9 -23 1.99899 host avmlp-osd-011 10 hdd 1.99899 osd.10 -25 1.99899 host avmlp-osd-012 11 hdd 1.99899 osd.11 -27 1.99899 host avmlp-osd-013 12 hdd 1.99899 osd.12 -29 1.99899 host avmlp-osd-014 13 hdd 1.99899 osd.13 -31 1.99899 host avmlp-osd-015 14 hdd 1.99899 osd.14 -33 1.99899 host avmlp-osd-016 15 hdd 1.99899 osd.15 -35 1.99899 host avmlp-osd-017 16 hdd 1.99899 osd.16 -37 1.99899 host avmlp-osd-018 17 hdd 1.99899 osd.17 -39 1.99899 host avmlp-osd-019 18 hdd 1.99899 osd.18 -41 1.99899 host avmlp-osd-020 19 hdd 1.99899 osd.19
Get actual map
This command export the map from the running cluster, the file is binary:
ceph osd getcrushmap -o crushmap
Convert the map to text
crushtool -d crushmap -o crushmap.txt
the map file
The file has the hierarchy of the tree as follows:
- root
- datacenter (if defined)
- rack (if defined)
- host
Each item is defined as this example:
| rack | root default {
id -1 # do not change unnecessarily
id -2 class hdd # do not change unnecessarily
# weight 39.980
alg straw2
hash 0 # rjenkins1
item itconic weight 0.000
item mediacloud weight 0.000
}
|
|---|---|
| datacenter | datacenter itconic {
id -44 # do not change unnecessarily
id -46 class hdd # do not change unnecessarily
# weight 0.000
alg straw2
hash 0 # rjenkins1
item datacenter01 weight 0.000
}
|
So each “node” define the child “nodes” with the item keyword.
Compile the new map
crushtool -c crushmap.txt -o crushmap.new
Apply the new map
ceph osd setcrushmap -i crushmap.new
Review the Map
ceph osd crush tree
Sample:
avmlp-osm-001 ~ :( # ceph osd crush tree ID CLASS WEIGHT TYPE NAME -1 0 root default -44 0 datacenter itconic -43 0 rack datacenter01 -3 1.99899 host avmlp-osd-001 0 hdd 1.99899 osd.0 -7 1.99899 host avmlp-osd-003 2 hdd 1.99899 osd.2 -11 1.99899 host avmlp-osd-005 4 hdd 1.99899 osd.4 -15 1.99899 host avmlp-osd-007 6 hdd 1.99899 osd.6 -19 1.99899 host avmlp-osd-009 8 hdd 1.99899 osd.8 -23 1.99899 host avmlp-osd-011 10 hdd 1.99899 osd.10 -27 1.99899 host avmlp-osd-013 12 hdd 1.99899 osd.12 -31 1.99899 host avmlp-osd-015 14 hdd 1.99899 osd.14 -35 1.99899 host avmlp-osd-017 16 hdd 1.99899 osd.16 -39 1.99899 host avmlp-osd-019 18 hdd 1.99899 osd.18 -48 0 datacenter mediacloud -47 0 rack datacenter02 -5 1.99899 host avmlp-osd-002 1 hdd 1.99899 osd.1 -9 1.99899 host avmlp-osd-004 3 hdd 1.99899 osd.3 -13 1.99899 host avmlp-osd-006 5 hdd 1.99899 osd.5 -17 1.99899 host avmlp-osd-008 7 hdd 1.99899 osd.7 -21 1.99899 host avmlp-osd-010 9 hdd 1.99899 osd.9 -25 1.99899 host avmlp-osd-012 11 hdd 1.99899 osd.11 -29 1.99899 host avmlp-osd-014 13 hdd 1.99899 osd.13 -33 1.99899 host avmlp-osd-016 15 hdd 1.99899 osd.15 -37 1.99899 host avmlp-osd-018 17 hdd 1.99899 osd.17 -41 1.99899 host avmlp-osd-020 19 hdd 1.99899 osd.19
External documentation
ceph/modifying_crush_map.1563434264.txt.gz · Last modified: 2019/07/18 07:17 by 127.0.0.1