Saturday, August 10, 2013, 9:27:02 PM, you wrote: > I'm a little uncertain on this:
> "When a request is received from a client volume assignment is done > in parallel for each tier quality". > This seems like it could be potentially expensive. For example, an object > that is in all cache tiers would have to examine that object in the cache > before saying it's "readable" or not, right? So lets say an object is in SSD > and rotational disk, and the Oracle queries this in parallel, it'll cause us > to become bound by the speed of the rotational disk, no? No. Currently volume assignment is done without reference to disk. I think in this case the oracle would be presumed to consult an in memory directory (as is done now). This is the point of the "RW" return - "I think I have it, but maybe my directory is out of date". In that case the actual I/O is sequential as the tier volume attempts to read the actual object. The oracle determines the probe order of the tiers that returned READ or RW. I'll take a look in more detail about the exact sequencing here. Something to think about on the road.
