Hello, On 08/20/2010 05:18 PM, Ric Wheeler wrote: > On 08/20/2010 09:22 AM, Christoph Hellwig wrote: >> FYI: here's a little writeup to document the new cache flushing scheme, >> intended to replace Documentation/block/barriers.txt. Any good >> suggestion for a filename in the kernel tree? >> > > I was thinking that we might be better off using the "durable > writes" term more since it is well documented (at least in the > database world, where it is the "D" in ACID properties). Maybe > "durable_writes_support.txt" ? The term is very foreign to people outside of enterprise / database loop. writeback-cache.txt or write-cache-control.txt sounds good enough to me. >> The Linux block layer provides a two simple mechanism that lets filesystems >> control the caching behavior of the storage device. These mechanisms are >> a forced cache flush, and the Force Unit Access (FUA) flag for requests. >> > > Should we mention that users can also disable the write cache on the > target device? > > It might also be worth mentioning that storage needs to be properly > configured - i.e., an internal hardware RAID card with battery > backing needs can expose itself as a writethrough cache *only if* it > actually has control over all of the backend disks and can > flush/disable their write caches. It might be useful to give several example configurations with different cache configurations. I don't have much experience with battery backed arrays but aren't they suppose to report write through cache automatically? Thanks. -- tejun -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
