On Mon, Jun 28, 2010 at 09:53:20AM -0400, Narendran Ganapathy wrote: > This patch extends the dm-path-selector interface to allow path selectors to > use extra information from the IO request when selecting a path. > To do location based routing, we need the address information of the request. What other inputs - in addition to offset - will the path selector need to take into account to make its decision and how will it get those inputs? Presumably you envisage some sort of semi-static or cached information, and not asking the hardware before every piece of I/O? How many ranges are there likely to be in this offset-based routing table? How frequently is the offset-based routing table likely to change? As Hannes points out, the dm table layer is already designed to handle offset-based routing, so I'll need some convincing there's a need to duplicate part of this inside path selectors. If this information is rapidly changing - many reconfigurations per minute, then we may need to consider some in-kernel solution. Otherwise I'll be seeking solutions performing the reconfiguration from userspace first. > We also propose extending the dm_mpath_io structure used to hold information I'll consider proposals for any new fields alongside patches that make good use of them, but I won't add fields in advance. Alasdair -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
