On Fri, Nov 07, 2008 at 02:44:08PM -0500, jim owens wrote: > To do that you kind of have to build a filesystem into the > block layer to persistently store "mapped/unmapped blocks > in chunk" and then do the "unmap-this-chunk" when a region > is all unmapped. > > 250 MB per 1TiB 512b sector disk for a simple 1-bit-per-sector > state. And that assumes you don't replicate it for safety. > That is what the array vendors are trying to avoid by pushing > it off to the OS. And it's what the OS people are trying to avoid having to incorporate by pushing back on the array vendors. > Whoever supports thin provisioning better get their unmapping > correct because those big customers will be looking for who > to blame if they don't get all the features. It's fairly clear that it's the array vendors at fault here. They've designed a shitty product and they're trying to get us to compensate. -- Matthew Wilcox Intel Open Source Technology Centre "Bill, look, we understand that you're interested in selling us this operating system, but compare it to ours. We can't possibly take such a retrograde step." -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
