HM4 is an NoSQL database with Redis interface https://github.com/nmmmnu/HM4/.
All tests are made on i7 6700K with 32 GB RAM on Linux 7.0.9 with a software RAID6 consisting of 6 spinning HDDs (four WDC RED at 5400 rpm, and two Ultrastars at 7200 rpm).
The disks are connected via an LSI Inspur 9211-8i 6Gbps host bus adapter (HBA mode).
The merge process was executed on 17 files: 16 files of 7.1 GB each and one file of 1.5 GB.
The resulting database file size is 114 GB (+ 7.3 GB index file).
This means the mmap-ing about 115 GB in 17 files and then create 4 files with total size of 121 GB.
All mmap's are madvice'd as sequential.
During the tests, individual disks never reached 100% utilization, but the aggregate RAID block device did reach 100% under specific schedulers.
| # | Elevator | Time 1 [mm:ss] |
RAID 1 [util] |
Time 2 [mm:ss] |
RAID 2 [util] |
|---|---|---|---|---|---|
| 1 | bfq | 08:32 | 100% | 17:26 | ~70% |
| 2 | mq-deadline | 14:36 | 100% | 18:19 | ~70% |
| 3 | kyber | 16:35 | ~75% | 18:32 | ~75% |
| 4 | none | 17:01 | ~70% | 19:08 | ~70% |