On Tue, Apr 10, 2018 at 03:26:11PM +0530, Sayan Ghosh wrote: > > That said, having a hard-coded separation of flash vs. disks does not > > make sense, even from an intermediate development point of view. There > > definitely should be a block-device interface for querying what the > > actual layout is, perhaps something like the SMR zones? > > Yes, I agree, that the ideal situation would be to have a mechanism to > identify the segment boundaries automatically inside the LVM. But we > were not able to get a method to access the boundaries or rather the > location of a free block in each segment by such system call. > So, in order to just test out the system we proceeded by hardcoding > the boundaries as per our simulated LVM. But since this is not > practical we provided the TODO/FIX IT in those areas. We are still > looking for a good mechanism, and would welcome any > advice/suggestions. > > Also, we chose to use Ext4 since it is generally the most commonly > used file system in linux based systems. However, I am not aware if > the problem of getting the boundaries can be solved in a simpler > manner by using XFS. SSD for the data device, HDD for the realtime device, device auto-selection based on initial allocation size patchset like this one: https://marc.info/?l=linux-xfs&m=151190613327238&w=2 Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx
