Re: Unable to start libvirt VM when using cache tiering.

[Burkhard Linke <Burkhard.Linke@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>]

Hi,

On 08/05/2015 03:09 PM, Pieter Koorts wrote:

Hi,

This is my OSD dump below

#######################

osc-mgmt-1:~$ sudo ceph osd dump | grep pool

pool 0 'rbd' replicated size 3 min_size 2 crush_ruleset 0 object_hash rjenkins pg_num 128 pgp_num 128 last_change 43 lfor 43 flags hashpspool tiers 1 read_tier 1 write_tier 1 stripe_width 0

pool 1 'ssd' replicated size 3 min_size 2 crush_ruleset 1 object_hash rjenkins pg_num 128 pgp_num 128 last_change 44 flags hashpspool,incomplete_clones tier_of 0 cache_mode writeback hit_set bloom{false_positive_probability: 0.05, target_size: 0, seed: 0} 0s x0 stripe_width 0

 #######################

I have also attached my crushmap (plain text version) if that can provide any detail too.

This is the setup of my VM cache pool:
pool 9 'ssd_cache' replicated size 2 min_size 1 crush_ruleset 2 object_hash rjenkins pg_num 128 pgp_num 128 last_change 182947 flags hashpspool,incomplete_clones tier_of 5 cache_mode writeback target_bytes 500000000000 target_objects 1000000 hit_set bloom{false_positive_probability: 0.05, target_size: 0, seed: 0} 3600s x1 min_read_recency_for_promote 1 stripe_width 0

You proabably need to set at least either target_bytes or target_objects. These are the values the flush/evict ratios of cache pools refer to.

Best regards,
Burkhard

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