Hi Austin, and thanks for your reply. Le lundi 16 juin 2014, 07:09:55 Austin S Hemmelgarn a écrit : > > What mkfs.btrfs looks at is > /sys/block/<whatever-device>/queue/rotational, if that is 1 it knows > that the device isn't a SSD. I believe that LVM passes through whatever > the next lower layer's value is, but dmcrypt (and by extension LUKS) > always force it to a 1 (possibly to prevent programs from using > heuristics for enabling discard)
In the current "running condition", the system clearly sees this is *not* rotational, even thru the LVM/dmcrypt stack : # mount | grep btrfs /dev/mapper/VG-LINUX on / type btrfs (rw,noatime,seclabel,compress=lzo,ssd,discard,space_cache,autodefrag) # ll /dev/mapper/VGV-LINUX lrwxrwxrwx. 1 root root 7 16 juin 09:21 /dev/mapper/VG-LINUX -> ../dm-1 # cat /sys/block/dm-1/queue/rotational 0 ...However, at mkfs.btrfs time, it migth well not have seen it, as I made it from a live USB key in which both the lvm.conf and crypttab had not been taylored to allow "trim" commands... However, now that the FS is created, I still wonder whether I should use a rebalance to change the metadata from DUP to SINGLE, or if Id' better stay with DUP... Kind regards. -- Swâmi Petaramesh <sw...@petaramesh.org> http://petaramesh.org PGP 9076E32E -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
