Zitat von Emmanuel Florac <eflorac@xxxxxxxxxxxxxx>:
Le Thu, 29 Sep 2016 17:40:56 +0200
"Jens-U. Mozdzen" <jmozdzen@xxxxxx> écrivait:
Another counter-example: You wouldn't put LVM on a disk that's
intended as a (100%) MD-RAID volume, and add an LV as RAID member...
you'll add a partition table for a reason, but no extra layer
between the partition and the RAID stuff.
I agree, but usually you wouldn't partition an MD-RAID either, would
you? OSDs are still holding (so far) ordinary filesystems locally
mounted on the nodes (except for BlueStore AFAIK).
in both cases, it's a matter of your point of view.
I treat bcache as a means to introduce "hybrid disks" (or rather
hybrid block devices), where I can take standard HDDs and extend them
by adding SSD caching at the OS layer - instead of buying special RAID
controllers or hybrid disks. This adds a layer of flexibility (in
terms of "buying choice") for me.
Anyway bcache would mostly make sense for the journal, much less for
the data section, so wouldn't it better to use bcache (or flash) for
journal/metadata only?
SSDs provide a lot of space nowadays, why not speed up all accesses?
This will lead to faster persistence and probably faster read access
as well (depending on your workload).
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