Each vnode already opens a separate bitcask, therefore there isn't any necessary factor preventing the desired behavior. It's just not coded that way. While an individual bitcask must be a single directory, there is no reason all vnodes need to open bitcasks within a shared root directory.
Luckily, it's easy to change this behavior. In fact, I played around with the idea awhile back. This question prompted me to find/release the code: https://github.com/jtuple/riak_kv/commit/a8ab33224651e6850aed385e4c05c1993916a3e5 That commit should apply against riak-0.14.1. It extends the bitcask data_root config option to allow for multiple root paths as well as a selection strategy (random or spread). Random just randomly chooses one of the directories. Spread picks the directory containing the fewest already-opened bitcasks -- although, this is a soft guarantee since no effort is taken to address multiple vnodes choosing a directory concurrently. Using paths that correspond to different mounted drives should do the trick. -Joe riak opens a new bitcask for each vnode. Therefore, while bitcask itself requires a single directory, forcing all vnodes to use the same root directory is On Mon, Mar 21, 2011 at 5:29 PM, Greg Nelson <gro...@dropcam.com> wrote: > Hello, > We are currently evaluating Riak for an application that will store large > amounts of data in a write-heavy pattern. We'd like to pack many disks into > each machine. Currently, it appears that Bitcask uses exactly one directory > to store data. What is the best way to have it use multiple disks? Is this > something Innostore would handle better? > We'd like to avoid RAID since we'll be paying for redundancy at a higher > level with Riak (N=3, etc.). > We'd also like to avoid a JBOD type setup where a single disk failure brings > the whole node down, as we'll obviously be increasing those odds with each > disk. > What I'm wondering is, can each node distribute its vnodes across many > disks? And if one of those disks fails, will Riak handle that appropriately > (i.e., the other vnodes continue to operate normally and hand-off data when > the new disk comes online)? > Thanks! > Greg > _______________________________________________ > riak-users mailing list > riak-users@lists.basho.com > http://lists.basho.com/mailman/listinfo/riak-users_lists.basho.com > > _______________________________________________ riak-users mailing list riak-users@lists.basho.com http://lists.basho.com/mailman/listinfo/riak-users_lists.basho.com
