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martinsumner 2017-02-08 17:11:51 +00:00
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docs/VOLUME.md
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@ -60,7 +60,7 @@ An identical test was run as above, but with d2.2xlarge instances, so that perfo
Although append_only writes are being used, almost every write still requires a disk head movement even if the server had all reads handled by in-memory cache (as there are normally more vnodes on the server than there are disk heads). It is clear that without a Flash-Backed Write Cache, spinning disks are unusable as the sole storage mechanism.
Also tested was d2.2zlarge clusters, but without sync_on_write. Results were:
Also tested was this same d2.2xlarge cluster, but without sync_on_write. Results were:
leveled Results | eleveldb Results
:-------------------------:|:-------------------------:
@ -68,6 +68,8 @@ leveled Results | eleveldb Results
This test showed a <b>26.7%</b> improvement in throughput when using LevelEd. The improvement in tail latency in this test had leveled at about <b>25%</b> of the tail latency of leveldb.
This indicates that without sync_on_writes, there remains potential value in using HDD drives, with either leveldb and leveled. It seems reasonably likely (although it remains unproven) that spinning drives with a hardware RAID and flash-backed write cache may perform reasonably even with sync on writes.
## Riak Cluster Test - 3
to be completed ..