On 02/28/2017 02:35 AM, Shaohua Li wrote: > On Tue, Feb 21, 2017 at 08:43:54PM +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. 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. > > Generally looks ok, I replied separatly. I'd like to make sure the new format > will be supported by Intel RSTe, and intel will continue working on this. PPL for IMSM is going to be included in RSTe implementations starting with the upcoming Xeon platforms and Intel will continue supporting and maintaining it. Thanks, Artur -- 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
