SMR vs CMR HDD
petasanrd911
19 Posts
June 21, 2021, 7:24 pmQuote from petasanrd911 on June 21, 2021, 7:24 pmJust curious, as you may have read ther was an issue where drive manufacturers where putting out NAS drives with SMR technology which has a performance issue when used in raid setups. Since Ceph uses each drive as an OSD it shouldn't matter if the drives are SMR vs CMR right?
Just curious, as you may have read ther was an issue where drive manufacturers where putting out NAS drives with SMR technology which has a performance issue when used in raid setups. Since Ceph uses each drive as an OSD it shouldn't matter if the drives are SMR vs CMR right?
Shiori
86 Posts
December 17, 2021, 1:46 pmQuote from Shiori on December 17, 2021, 1:46 pmI can confirm that Ceph does not care but there is a cost in IOPS. SMR drives take longer to make changes since they must uproot every sector adjacent to the one to be written. This increase in write delay makes the total write throughput of the cluster go down however for pure read transactions they are just as quick.
We have found SMR drives to be best used in video playback systems as you only write once but read many times. Or in bulk backup systems where you continually write in sequence without modifying writes. For a dynamic system like Ceph, we stick to CMR/PMR drives. They are smaller but they are way faster.
I can confirm that Ceph does not care but there is a cost in IOPS. SMR drives take longer to make changes since they must uproot every sector adjacent to the one to be written. This increase in write delay makes the total write throughput of the cluster go down however for pure read transactions they are just as quick.
We have found SMR drives to be best used in video playback systems as you only write once but read many times. Or in bulk backup systems where you continually write in sequence without modifying writes. For a dynamic system like Ceph, we stick to CMR/PMR drives. They are smaller but they are way faster.
SMR vs CMR HDD
petasanrd911
19 Posts
Quote from petasanrd911 on June 21, 2021, 7:24 pmJust curious, as you may have read ther was an issue where drive manufacturers where putting out NAS drives with SMR technology which has a performance issue when used in raid setups. Since Ceph uses each drive as an OSD it shouldn't matter if the drives are SMR vs CMR right?
Just curious, as you may have read ther was an issue where drive manufacturers where putting out NAS drives with SMR technology which has a performance issue when used in raid setups. Since Ceph uses each drive as an OSD it shouldn't matter if the drives are SMR vs CMR right?
Shiori
86 Posts
Quote from Shiori on December 17, 2021, 1:46 pmI can confirm that Ceph does not care but there is a cost in IOPS. SMR drives take longer to make changes since they must uproot every sector adjacent to the one to be written. This increase in write delay makes the total write throughput of the cluster go down however for pure read transactions they are just as quick.
We have found SMR drives to be best used in video playback systems as you only write once but read many times. Or in bulk backup systems where you continually write in sequence without modifying writes. For a dynamic system like Ceph, we stick to CMR/PMR drives. They are smaller but they are way faster.
I can confirm that Ceph does not care but there is a cost in IOPS. SMR drives take longer to make changes since they must uproot every sector adjacent to the one to be written. This increase in write delay makes the total write throughput of the cluster go down however for pure read transactions they are just as quick.
We have found SMR drives to be best used in video playback systems as you only write once but read many times. Or in bulk backup systems where you continually write in sequence without modifying writes. For a dynamic system like Ceph, we stick to CMR/PMR drives. They are smaller but they are way faster.