I've experimented with different striped volumes in vinum under FreeBSD 8.2-release. I have current hardware (Intel i5 processor, adequate MB and 8GB RAM).
My test-setup consists of 2 or 4 disks in a volume, each disk is 2TB, "Green" line Seagate and Western Digital; i.e. consumer disks at 5400RPM. These are in my server, while my desktop that's connected to it (via Gbit LAN) has a quick SSD.
My problem is that I get better performance (i.e. read/write speeds) over my Gbit LAN when I access my single "Black" Western Digital 2TB, than when I access my vinum volumes.
- Black WD single disk: read = write = 90-105 MB/s
- vinum volumes, all setups: read = 80 MB/s ; write = 50 MB/s
The vinum configurations I've tried are:
drive a device /dev/ad32 drive b device /dev/ad34 drive c device /dev/ad26 drive d device /dev/ad28 volume test1 plex org striped 512k sd length 2048m drive a sd length 2048m drive b sd length 2048m drive c sd length 2048m drive d
drive a device /dev/ad32 drive b device /dev/ad34 volume test2 plex org striped 512k sd length 1907728m drive a sd length 1907728m drive b
test1 with different stripe lengths (512k, 64k, 2048k), but the speeds are the same. Also, I notice no difference in speeds between
test2, which I find very strange, considering these are striped volumes and disk-count therefore should matter.
Does anyone have a clue why this happens and what I can do to tune/speed-up vinum to at least outspeed my single HDD? Should I consider other options for performance (ZFS w/RAIDZ etc)?
More info (edit)
dmesg about the disks:
- ad26: 1907729MB [ST2000DL003 9VT166 CC32] at ata13-master UDMA100 SATA 6Gb/s
- ad28: 1907729MB [ST2000DL003 9VT166 CC32] at ata14-master UDMA100 SATA 3Gb/s
- ad32: 1907729MB [WDC WD20EARX-00PASB0 51.0AB51] at ata16-master UDMA100 SATA 3Gb/s
- ad34: 1907729MB [WDC WD20EARX-00PASB0 51.0AB51] at ata17-master UDMA100 SATA 3Gb/s
All disks are connected to onboard SATA-controller on my motherboard; Asus P8P67 Deluxe.
When testing ad32 as a single disk, I get write-speed at about 60-70MB/s, read-speed at about 80-90MB/s.
All testing done with one large file of about 2.5GB.
The point: my disks perform slower in a striped volume than alone... Suggestions?