On Thu, Aug 25, 2016 at 7:21 AM, marcin@mejor.pl wrote:

W dniu 24.08.2016 o 08:52, Kent Overstreet pisze:
[...]

Hi!

quoted

Hey, sorry for the long delay, been sick past several days.

I was afraid that I'm asking to easy question:) And I hope everything 
is
fine with you now!

quoted

The way arguments
were passed to bcache format was a holdover from old style 
make-bcache, and
didn't make much sense for bcachefs - -C was used for all devices, 
and --tier
specifies fast devices and slow devices.

I finally got around to redoing the option parsing so we don't need 
the -C
argument today - update your bcache tools, and the command you want 
is now:

bcache format --tier 0 /dev/sde1 --tier 1 /dev/sdd1

(assuming sde1 is your fast device and sdd1 is your slow device).

Does it means that cache is unavailable and only tiering will be in 
bcachefs?
And... How to mount tiered FS? When I pass one device in mount I'm 
getting:
 bcache: bch_open_as_blockdevs() register_cache_set err insufficient 
devices

Tiering gets you all the advantages of caching, plus you can (with some 
effort) have the combined filesystem size be the sum of the SSD + HDD 
capacities, rather than the capacity be determined solely by the 
capacity of the slow tier (this is not currently the case for bcachefs).

To mount a tiered FS you can either pass all the relevant devices to 
mount, like:
    mount -t bcache /dev/sda:/dev/sdb:/dev/sdc /mountpoint
(I haven't tested this recently) or ensure that all the relevant 
devices have been registered with bcache, like so:
    echo /dev/sda | sudo tee /sys/fs/bcache/register_quiet
    echo /dev/sdb | sudo tee /sys/fs/bcache/register_quiet
    echo /dev/sdc | sudo tee /sys/fs/bcache/register_quiet
    mount -t bcache /dev/sdb /mountpoint
(you can use any member of the set as the device to mount in this case).