Hi all, There are a couple of looming features for ceph-disk: 1- Support for additional devices when using BlueStore. There can be up to three: the main device, a WAL/journal device (small, ~128MB, ideally NVRAM), and a fast metadata device (as big as you have available; will be used for internal metadata). 2- Support for setting up dm-cache, bcache, and/or FlashCache underneath filestore or bluestore. The current syntax of ceph-disk prepare [--dmcrypt] [--bluestore] DATADEV [JOURNALDEV] isn't terribly expressive. For example, the journal device size is set via a config option, not on the command line. For bluestore, the metadata device will probably want/need explicit user input so they can ensure it's 1/Nth of their SSD (if they have N HDDs to each SSD). And if we put dmcache in there, that partition will need to be sized too. Another consideration is that right now we don't play nice with LVM at all. Should we? dm-cache is usually used in conjunction with LVM (although it doesn't have to be). Does LVM provide value? Like, the ability for users to add a second SSD to a box and migrate cache, wal, or journal partitions around? I'm interested in hearing feedback on requirements, approaches, and interfaces before we go too far down the road... Thanks! sage -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
