Bcache: Caching beyond just RAM [LWN.net]

Bcache: Caching beyond just RAM

Posted Jul 12, 2010 20:30 UTC (Mon) by rilder (guest, #59804)
Parent article: Bcache: Caching beyond just RAM

I recently came across L2ARC caching used in Solaris with ZFS + SSD. Is there any improvement or difference between that and bcache ?

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Bcache: Caching beyond just RAM

Posted Jul 15, 2010 22:59 UTC (Thu) by bill_mcgonigle (guest, #60249) [Link]

There's quite a bit of similarity. L2ARC is read-only, for wide random accesses. bcache aims to be read/write. ZFS also separates out its ZIL for writes. If I'm building a ZFS box I'd use a big MLC drive for the L2ARC and a smaller SLC drive for the ZIL as the workloads differ. You could probably set bcache to be read-only and put a filesystem's journal on a different drive if you wanted a more-like-ZFS segregation. bcache has the nice attribute of just being able to pull it and keep running - ZFS isn't usually set up that way. The L2ARC and ZIL have the checksumming today whereas bcache will get to that. Of course, bcache is much more general and useful in situations where ZFS has no relevance. It's good to have chisels and screwdrivers.