t. johnson wrote: >>> One would expect so, yes. But the usefulness of this is limited to the >>> cases where the entire working set will fit into an SSD cache. >>> >> Not entirely out of the question. SSDs can be purchased today >> with more than 500 GBytes in a 2.5" form factor. One or more of >> these would make a dandy L2ARC. >> http://www.stecinc.com/product/mach8mlc.php > > > Speaking of which.. what's the current limit on L2ARC size? Gathering tidbits > here and there (7000 storage line config limits, FAST talk given by Bill > Moore) there are indications that L2ARC can only be ~500GB?
There is no limits on the size of the L2ARC that I could fine implemented in the source code. However every buffer that is cached on an L2ARC device needs an ARC header in the in memory ARC that points to it. So in practical terms there will be a limit on the size of an L2ARC based on the size of physical ram. For example a machine with 512 MegaByte RAM and a 500GByte SSD L2ARC is probably pretty silly. I'll leave it as an exercise to the reader to work out how much core memory is needed based on the sizes of arc_buf_t (0x30) and arc_buf_hdr_t (0xf8). -- Darren J Moffat _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
