On Jun 23, 2008, at 1:20 PM, Darren Reed wrote: > eric kustarz wrote: >> >> On Jun 23, 2008, at 1:07 PM, Darren Reed wrote: >> >>> Tim Haley wrote: >>>> .... >>>> primarycache=all | none | metadata >>>> >>>> Controls what is cached in the primary cache (ARC). If set to >>>> "all", then both user data and metadata is cached. If set to >>>> "none", then neither user data nor metadata is cached. If >>>> set to >>>> "metadata", then only metadata is cached. The default >>>> behavior is >>>> "all". >>>> >>> >>> The description above kind of implies that user data is somehow >>> separate to metadata >>> but it isn't possible to say cache only user data (with the text >>> given.) Is this just an >>> oversight or is this really saying you cannot cache only the user >>> data? >> >> We couldn't come up with any realistic workload that would want to >> cache user data but not metadata, so we're not allowing it. >> >> We can always add the option later, but if someone has a realistic >> use case for it, i'd be happy to add it now. > > It's not so much the "why", but maybe I'd like to say the primarycache > gets metadata and the secondary cache gets user data (or vice versa.) > If that make sense? Or would that require linkage between metadata > and user data (across cache boundaries) in order to maintain sanity?
It is the "why". If there's no reason to do it, then we shouldn't allow it (adds more complexity, more confusion, more ways for a customer to shoot themselves in the foot). However, if there is a legitimate use case, let's discuss that. eric
