Hi Nikolaus,

Zitat von Nikolaus Rath [off-list ref]:

Hello,

The internet claims that using bcache with LVM is not a good idea
(eg. on https://wiki.archlinux.org/index.php/Bcache )- but I wasn't able
to find any substantial information other than this general
recommendation.

looking at that article, it only references possibly ill-handled  
"discard" operations, when running bcache on top of LVM.

The article itself does positively mention sub-dividing bcache devices  
using LVM.

Is this still (or has ever been) correct? If so, what issues can arise?
And does this happen only when using bcache on top of an LVM LV, or also
when using a bcache device as an LVM PV?

We're running bcache between MD-RAID (RAID6 for the HDD backing store  
and RAID1 for caching SSDs) and LVM2 (using bcache0 as the only PV for  
the volume group) without any noticeable problem, for moderate to  
significant load (SAN/NAS servers with NFS, Samba, and virtual  
machines' storage via SCST/FC and SCST/iSCSI).

Regards,
Jens