File:Gmirror-performance.png
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Chart showing performance of gmirror (and some proprietary RAID1 hardware implementations).
System:
FreeBSD OS: amd64 6.2-RELEASE
Linux OS: amd64 Ubuntu Server 7.04
Athlon X2 5000+, 2GB RAM
3x Western Digital 250GB drives (WDC WD2500JS-22NCB1 10.02E02 SATA-300)
2x Western Digital 500GB drives (WDC WD5000AAKS-00YGA0 12.01C02)
Nvidia nForce onboard RAID controller
Promise TX2300 RAID controller
Each process shown in the graph is a cp to /dev/null of an individually generated 3200MB random binary file (using dd if=/dev/random bs=16m count=200).
The "split" balance algorithm was also tested but resolved in universally horrible performance, so was not included on the graph.
For these tests, FreeBSD's read-ahead cache value was GREATLY increased from 6.2-RELEASE's default of 8: sysctl -w vfs.read_max=128. Similarly, Ubuntu's read-ahead cache value was drastically increased from system default of hdparm /dev/md0 -a256 to hdparm /dev/md0 -a4096. Changing these values made TREMENDOUS differences in throughput - frequently doubling, sometimes even quintupling average transfer rate across tests.
Raw data follows:
Linux RAID1: 3x250/2x500 68 152 213 251 258 * Hdparm -a 4096 Linux RAID1: 3x250 62 123 155 158 162 * Hdparm -a 4096 Linux RAID1: 2x250 62 114 108 102 110 * Hdparm -a 4096 31s delta on 4-copy... 30-sec delta on 5-copy Nvidia onboard RAID1: 2x250 60 108 90 96 100 * 15 secs delta on 2-process copy / 38 seconds on 5-process copy Gmirror: 3x250/2x500 round-robin 63 73 69 71 72 Baseline: 1x500 76 70 72 72 72 Baseline: 1x250 56 56 55 55 56 Gmirror: 3x250 round-robin 59 53 53 56 55 Promise TX-2300 RAID1: 2x250 61 52 54 55 57 * 15 sec delta on 5-process copy Gmirror: 3x250/2x500 split 128k 54 50 47 47 47 Gmirror: 2x250 round-robin 58 49 51 51 50 Gmirror: 2x250 split 128k 55 47 47 47 48 Gmirror: 3x250 split 128k 55 46 49 55 54
"Delta" in raw numbers refers to individual processes finishing significantly faster than others, though all were started simultaneously.
File history
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| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| current | 23:25, 27 December 2007 | | 650 × 400 (23 KB) | Jimbo (Talk | contribs) | |
| 23:13, 27 December 2007 |  | 1,300 × 800 (25 KB) | Jimbo (Talk | contribs) | ||
| 21:38, 27 December 2007 |  | 650 × 400 (23 KB) | Jimbo (Talk | contribs) | (added Linux RAID1 data) | |
| 20:50, 26 December 2007 |  | 650 × 400 (22 KB) | Jimbo (Talk | contribs) | ((oops - wrong file uploaded first time)) | |
| 20:48, 26 December 2007 |  | 650 × 400 (22 KB) | Jimbo (Talk | contribs) | (Chart showing performance of gmirror (and some proprietary RAID1 hardware implementations) under amd64 6.2-RELEASE, Athlon X2 5000+, 2GB RAM. Each file copied in the graph was individually generated using dd if=/dev/random bs=16m count=200 (3200MB file).) |
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