Crush map example

[Darryl Bond <dbond@xxxxxxxxxxxxx>]

I have a cluster of 3 hosts each with 2 SSD and 4 Spinning disks.
I used the example in th ecrush map doco to create a crush map to place
the primary on the SSD and replica on spinning disk.

If I use the example, I end up with objects replicated on the same host,
if I use 2 replicas.

Question 1, is the documentation on the rules correct, should they
really be both ruleset 4 and why? I used ruleset 5 for the ssd-primary.
      rule ssd {
              ruleset 4
              type replicated
              min_size 0
              max_size 10
              step take ssd
              step chooseleaf firstn 0 type host
              step emit
      }

      rule ssd-primary {
              ruleset 4
              type replicated
              min_size 0
              max_size 10
              step take ssd
              step chooseleaf firstn 1 type host
              step emit
              step take platter
              step chooseleaf firstn -1 type host
              step emit
      }

Question 2, Is there any way to ensure that the replicas are on
different hosts when we use double rooted trees for the 2 technologies?
Obviously, the simplest way is to have them on separate hosts.

For the moment, I have increased the number of replicas in the pool to 3
which does ensure that there is at least copies spread across multiple
hosts.

Darryl


The contents of this electronic message and any attachments are intended only for the addressee and may contain legally privileged, personal, sensitive or confidential information. If you are not the intended addressee, and have received this email, any transmission, distribution, downloading, printing or photocopying of the contents of this message or attachments is strictly prohibited. Any legal privilege or confidentiality attached to this message and attachments is not waived, lost or destroyed by reason of delivery to any person other than intended addressee. If you have received this message and are not the intended addressee you should notify the sender by return email and destroy all copies of the message and any attachments. Unless expressly attributed, the views expressed in this email do not necessarily represent the views of the company.
_______________________________________________
ceph-users mailing list
ceph-users@xxxxxxxxxxxxxx
http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com