On Tue, Mar 29, 2016 at 01:35:32AM +0530, Pradeep Jindal wrote: > > > I am facing a weird problem, I earlier had a configuration wherein my > > > backing device was a logical volume (LVM) backed by 3 software RAID0 > > > arrays having 2x1TB disks each, so totally 6TB of storage for backing > > > device and 300GB logical volume (LVM) backed by SSD as a caching > > > device. Both were configured as a cache set and I was getting around > > > 84% cache hit ratio. > > > > > > Now, I have changed the backing device to a bare (no LVM, no raid) 6TB > > > disk while everything else stays same (caching device on LVM, 300GB) > > > and for exactly same workload I am only getting 58-60% cache hit > > > ratio. > > > > > > I am confused, what could be the reason? > > > > Full stripe size writes are configured according to the backing device, > > for example. > Didn't quite get it, could you please elaborate? Backing devices that advertise a stripe size cause bcache to enable a mode where it tries to always write a full stripe to the backing devices, hence changing behavior of the cache. -- Vojtech Pavlik Director SuSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-bcache" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
