On 06/08/14 13:07, debian Only wrote: > Thanks for your reply. > I have found and test a way myself.. and now share to others > > > >>>>>Begin>>> On Debian >>> > root at ceph01-vm:~# modprobe brd rd_nr=1 rd_size=4194304 max_part=0 > root at ceph01-vm:~# mkdir /mnt/ramdisk > root at ceph01-vm:~# mkfs.btrfs /dev/ram0 You should avoid creating filesystems on top of the ramdisk for the journal. Either create a single ramdisk, and create partitions on it for each journal, or create multiple ramdisks and use each ramdisk whole. Put the journals on these raw partitions / block devs. Using a filesystem (especially one such as btrfs) on top of a ramdisk just creates unnecessary overhead. Alternatively use a tmpfs instead of ramdisk. Just create a single tmpfs that is big enough to hold all your journals, then symlink each /var/lib/ceph/osd/ceph-XX/journal to a unique file on the tmpfs. Beware however that tmpfs _can_ be swapped out to disk, if the system starts to run low on physical memory.
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