On Thu, Mar 09, 2017 at 09:59:56AM +0100, Artur Paszkiewicz wrote: > This series of patches implements the Partial Parity Log for RAID5 arrays. The > purpose of this feature is closing the RAID 5 Write Hole. It is a solution > alternative to the existing raid5-cache, but the logging workflow and much of > the implementation is based on it. > > The main differences compared to raid5-cache is that PPL is a distributed log - > it is stored on array member drives in the metadata area and does not require a > dedicated journaling drive. Write performance is reduced by up to 30%-40% but > it scales with the number of drives in the array and the journaling drive does > not become a bottleneck or a single point of failure. PPL does not protect from > losing in-flight data, only from silent data corruption. More details about how > the log works can be found in patches 3 and 5. > > This feature originated from Intel RSTe, which uses IMSM metadata. PPL for IMSM > is going to be included in RSTe implementations starting with upcoming Xeon > platforms and Intel will continue supporting and maintaining it. This patchset > implements PPL for external metadata (specifically IMSM) as well as native MD > v1.x metadata. > > Changes in mdadm are also required to make this fully usable. Patches for mdadm > will be sent later. Looks good, I'll apply this series into next. There are some small issues I replied separately. Please send a separate patch to fix them if they make sense, I'll integrate them locally. Thanks, Shaohua -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
