I am having a problem with BCache.

I’ve followed the documentation and have my cache attached. Here is
what dmesg tells me:

[  372.622905] bcache: invalidating existing data
[  372.637517] bcache: registered cache device rssda1
[  400.704672] bcache: Caching dm-2 as bcache0 on set
16fd7139-f018-461c-9d9e-daa

I warmed up the cache by using an application (vdbench) to do random
reads over a 10GB region.

Everything looks good as the response time comes down as the cache
warms up. But, for some reason the cache_hit_rate is showing 90% and
yet I’m still seeing heavy activity to the disk device.

bwalker@nellis:~> cat
/sys/fs/bcache/16fd7139-f018-461c-9d9e-daa7666c7f1e/stats_total/cache_hit_ratio
94
bwalker@nellis:~>

Any ideas on why this might be happening are appreciated.

-brad w.