Several considerations on deployment:
1. How a traditional OSD(filestore, or bluestore W/O local cache) behavior if the OSD is selected as a PG member of the local-cache-pool?
hopefully the osd can just work as-is like an OSD with CACHE-FULL.
2. Compared to other *global* caching mode, local-cache-mode cannot scale cache tier/storage tier separately, which will be a big caveats in real production environment, especially for those case that the working set is consistent but the archival data amount is keeping increasing.
Overall it seems like a alternative for b-cache/flashcache/i-cas , more test or analysis is needed to understand the benefit of this approach over the existing b-cache solution.
Honggang(Joseph) Yang <eagle.rtlinux@xxxxxxxxx> 于2019年10月13日周日 下午8:47写道：
After the sysbench prepare operation is completed, about 48883MB of db
data is generated.
I set the fast partition to 30GB, so in the sysbench run stage,
eviction was taking place.
Mark Nelson <mnelson@xxxxxxxxxx> 于2019年10月12日周六 上午12:15写道：
>
> Hi Honggang,
>
>
> I personally I find this very exciting! I was hoping that we might
> eventually try local caching in bluestore especially given trends for
> larger NVMe devices and pmem. When you were running performance tests,
> did you run any tests where the data set size was significantly larger
> than the available "fast" local tier cache (ie so that eviction was
> taking place)? In the past, that's been the area we've really needed to
> focus on getting right.
>
>
> Mark
>
>
> On 10/11/19 11:04 AM, Honggang(Joseph) Yang wrote:
> > Hi,
> >
> > We implemented a new cache tier mode - local mode. In this mode, an
> > osd is configured to manage two data devices, one is fast device, one
> > is slow device. Hot objects are promoted from slow device to fast
> > device, and demoted from fast device to slow device when they become
> > cold.
> >
> > The introduction of tier local mode in detail is
> > https://tracker.ceph.com/issues/42286
> >
> > tier local mode: https://github.com/yanghonggang/ceph/commits/wip-tier-new
> >
> > This work is based on ceph v12.2.5. I'm glad to port it to master
> > branch if needed.
> >
> > Any advice and suggestions will be greatly appreciated.
> >
> > thx,
> >
> > Yang Honggang
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