Hi, list,
Ceph cache tier seems very promising for performance.
According to
http://ceph.com/docs/master/rados/operations/crush-map/#placing-different-pools-on-different-osds
<http://ceph.com/docs/master/rados/operations/crush-map/#placing-different-pools-on-different-osds>
, I need to create a new pool based on SSD OSDs。
Currently, I’ve two servers with several HDD-based OSDs. I mean to add one
SSD-based OSD for each server, and then use these two OSDs to build a cache
pool.
But I’ve found problems editing crushmap.
The example in the link use two new hosts to build SSD OSDs and then create a
new ruleset take the new hosts.
But in my environment, I do not have new servers to use.
Can I create a ruleset choose part of OSDs in a host?
For example, as the crushmap shown below, osd.2 and osd.5 are new added
SSD-based OSDs, how can I create a ruleset choose these two OSDs only and how
can I avoid default ruleset to choose osd.2 and osd.5?
Is this possible, or I have to add a new server to deploy cache tier?
Thanks.
host node0 {
id -2
alg straw
hash 0
item osd.0 weight 1.0 # HDD
item osd.1 weight 1.0 # HDD
item osd.2 weight 0.5 # SSD
}
host node1 {
id -3
alg straw
hash 0
item osd.3 weight 1.0 # HDD
item osd.4 weight 1.0 # HDD
item osd.5 weight 0.5 # SSD
}
root default {
id -1 # do not change unnecessarily
# weight 1.560
alg straw
hash 0 # rjenkins1
item node0 weight 2.5
item node1 weight 2.5
}
# typical ruleset
rule replicated_ruleset {
ruleset 0
type replicated
min_size 1
max_size 10
step take default
step chooseleaf firstn 0 type host
step emit
}
van
chaofa...@owtware.com
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