Current Partial Parity Log implementation allows only single PPL to be written to particular member drive. In such case PPL entry is overwritten by every write as it's stored at the same sector of a drive. Such approach is suboptimal for SSD drives as it leads to increased write amplification factor due to write-after-write limitations. This patchset changes the implementation by extending PPL area to 1MB. PPL is not stored at fixed location but multiple PPLs are written in a circular buffer. There is at most one valid PPL at any time (latest one). Recovery algorithm stays the same. The main benefits of this approach are increased drive lifespan and in some cases improved performance. Pawel Baldysiak (2): md: Runtime support for multiple ppls raid5-ppl: Recovery support for multiple partial parity logs drivers/md/md.c | 16 +++- drivers/md/md.h | 1 + drivers/md/raid0.c | 3 +- drivers/md/raid1.c | 3 +- drivers/md/raid5-ppl.c | 171 +++++++++++++++++++++++++++++++---------- drivers/md/raid5.c | 1 + include/uapi/linux/raid/md_p.h | 4 +- 7 files changed, 152 insertions(+), 47 deletions(-) -- 2.13.4 -- 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
