| Message ID | 20200602110956.121170-1-hare@suse.de (mailing list archive) |
|---|---|
| Headers | show |
| Series | dm-zoned: multiple drive support | expand |
On Tue, Jun 02 2020 at 7:09am -0400, Hannes Reinecke <hare@suse.de> wrote: > Hi all, > > here's the second version of my patchset to support multiple zoned > drives with dm-zoned. > This patchset: > - Converts the zone array to using xarray for better scalability > - Separates out shared structures into per-device structure > - Enforce drive-locality for allocating and reclaiming zones > - Lifts the restriction of 2 devices to handle an arbitrary number > of drives. > > This gives me a near-perfect scalability by increasing the write > speed from 150MB/s (for a cache and one zoned drive) to 300MB/s > (for a cache and two zoned drives). > > Changes to v1: > - Include reviews from Damien > - Reshuffle patches > Changes to v2: > - Add reviews from Damien > - Merge patches 'dynamic device allocation' and > 'support arbitrary number of devices' > - Fix memory leak when reading tertiary superblocks > Changes to v3: > - Add reviews from Damien > - Add patch to ensure correct device ordering I've picked this series up for 5.8 (yes, I know it is last minute). But I saw no benefit to merging the initial 2 device step in 5.8 only to then churn the code and interface to support an arbitrary number of devices in 5.9. Easier to support one major update to the code now. As such the target's version number was _not_ bumped from 2.0.0 to 3.0.0. I tweaked various patch headers (_please_ "dm zoned" instead of "dm-zoned" in commit subjects, also don't ever say "we" or "this patch" in a commit header... if you do, I am forced to rewrite the header). BTW, just so I feel like I said it: all these changes to use additional device(s) really seems like a tradeoff between performance and reduced MTBF -- there is increased potential for failure with each additional device that is added to the dm-zoned device... there I've said it ;) Thanks, Mike -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel
On 2020/06/03 7:27, Mike Snitzer wrote: > On Tue, Jun 02 2020 at 7:09am -0400, > Hannes Reinecke <hare@suse.de> wrote: > >> Hi all, >> >> here's the second version of my patchset to support multiple zoned >> drives with dm-zoned. >> This patchset: >> - Converts the zone array to using xarray for better scalability >> - Separates out shared structures into per-device structure >> - Enforce drive-locality for allocating and reclaiming zones >> - Lifts the restriction of 2 devices to handle an arbitrary number >> of drives. >> >> This gives me a near-perfect scalability by increasing the write >> speed from 150MB/s (for a cache and one zoned drive) to 300MB/s >> (for a cache and two zoned drives). >> >> Changes to v1: >> - Include reviews from Damien >> - Reshuffle patches >> Changes to v2: >> - Add reviews from Damien >> - Merge patches 'dynamic device allocation' and >> 'support arbitrary number of devices' >> - Fix memory leak when reading tertiary superblocks >> Changes to v3: >> - Add reviews from Damien >> - Add patch to ensure correct device ordering > > I've picked this series up for 5.8 (yes, I know it is last minute). But > I saw no benefit to merging the initial 2 device step in 5.8 only to > then churn the code and interface to support an arbitrary number of > devices in 5.9. Easier to support one major update to the code now. > > As such the target's version number was _not_ bumped from 2.0.0 to > 3.0.0. > > I tweaked various patch headers (_please_ "dm zoned" instead of > "dm-zoned" in commit subjects, also don't ever say "we" or "this patch" > in a commit header... if you do, I am forced to rewrite the header). > > BTW, just so I feel like I said it: all these changes to use additional > device(s) really seems like a tradeoff between performance and reduced > MTBF -- there is increased potential for failure with each additional > device that is added to the dm-zoned device... there I've said it ;) Yes, agreed. While the cache SSD + 1xSMR disk can I think have reasonable applications, more than 1 SMR disk without any data protection is indeed dangerous. However, I think that we now have a good base to improve this: duplication of zones across devices using reclaim should not be difficult to implement. That is a RAID1 level, to which we can even add more than one copy again with reclaim (dm-kcopyd comes in very handy for that). And I am still thinking of ways to erasure code zones across the multiple devices to raise the possible RAID levels :) Another approach would be to do intelligent stacking of dm-raid on top of dm-zoned devices. "intelligent" here means that in case of any drive failure, only a partial rebuild of the dm-zoned device with the failed drive is needed: one only needs to rebuild the sector chunks that the failed SMR drive was holding. > > Thanks, > Mike > >
On 6/3/20 12:27 AM, Mike Snitzer wrote: > On Tue, Jun 02 2020 at 7:09am -0400, > Hannes Reinecke <hare@suse.de> wrote: > >> Hi all, >> >> here's the second version of my patchset to support multiple zoned >> drives with dm-zoned. >> This patchset: >> - Converts the zone array to using xarray for better scalability >> - Separates out shared structures into per-device structure >> - Enforce drive-locality for allocating and reclaiming zones >> - Lifts the restriction of 2 devices to handle an arbitrary number >> of drives. >> >> This gives me a near-perfect scalability by increasing the write >> speed from 150MB/s (for a cache and one zoned drive) to 300MB/s >> (for a cache and two zoned drives). >> >> Changes to v1: >> - Include reviews from Damien >> - Reshuffle patches >> Changes to v2: >> - Add reviews from Damien >> - Merge patches 'dynamic device allocation' and >> 'support arbitrary number of devices' >> - Fix memory leak when reading tertiary superblocks >> Changes to v3: >> - Add reviews from Damien >> - Add patch to ensure correct device ordering > > I've picked this series up for 5.8 (yes, I know it is last minute). But > I saw no benefit to merging the initial 2 device step in 5.8 only to > then churn the code and interface to support an arbitrary number of > devices in 5.9. Easier to support one major update to the code now. > > As such the target's version number was _not_ bumped from 2.0.0 to > 3.0.0. > > I tweaked various patch headers (_please_ "dm zoned" instead of > "dm-zoned" in commit subjects, also don't ever say "we" or "this patch" > in a commit header... if you do, I am forced to rewrite the header). > > BTW, just so I feel like I said it: all these changes to use additional > device(s) really seems like a tradeoff between performance and reduced > MTBF -- there is increased potential for failure with each additional > device that is added to the dm-zoned device... there I've said it ;) > "We" (sic) are fully aware. And I'm looking into it. Thanks for merging it. Most appreciated. Cheers, Hannes
Hi all, here's the second version of my patchset to support multiple zoned drives with dm-zoned. This patchset: - Converts the zone array to using xarray for better scalability - Separates out shared structures into per-device structure - Enforce drive-locality for allocating and reclaiming zones - Lifts the restriction of 2 devices to handle an arbitrary number of drives. This gives me a near-perfect scalability by increasing the write speed from 150MB/s (for a cache and one zoned drive) to 300MB/s (for a cache and two zoned drives). Changes to v1: - Include reviews from Damien - Reshuffle patches Changes to v2: - Add reviews from Damien - Merge patches 'dynamic device allocation' and 'support arbitrary number of devices' - Fix memory leak when reading tertiary superblocks Changes to v3: - Add reviews from Damien - Add patch to ensure correct device ordering Hannes Reinecke (15): dm-zoned: add debugging message for reading superblocks dm-zoned: secondary superblock must reside on the same devices than primary superblock dm-zoned: improve logging messages for reclaim dm-zoned: add a 'reserved' zone flag dm-zoned: convert to xarray dm-zoned: temporary superblock for tertiary devices dm-zoned: add device pointer to struct dm_zone dm-zoned: add metadata pointer to struct dmz_dev dm-zoned: per-device reclaim dm-zoned: move random and sequential zones into struct dmz_dev dm-zoned: support arbitrary number of devices dm-zoned: allocate zone by device index dm-zoned: select reclaim zone based on device index dm-zoned: prefer full zones for reclaim dm-zoned: check superblock location drivers/md/dm-zoned-metadata.c | 463 +++++++++++++++++++++++++---------------- drivers/md/dm-zoned-reclaim.c | 95 +++++---- drivers/md/dm-zoned-target.c | 169 +++++++++------ drivers/md/dm-zoned.h | 77 ++++--- 4 files changed, 494 insertions(+), 310 deletions(-)