Shaf’s Log

With so many motherboard and PCI RAID devices being sold cheaply to the techie consumer it has to be noted that 99% of them are infact Fake RAID.

Ask yourself why buy a RAID card that costs £300+ when my cheap £30 motherboard has built in RAID ! Ask yourself indeed the difference between FakeRAID and real RAID ;)

Here are some performance benchmarks comparing FakeRAID vs Linux Software RAID…

Hardware

Setup A : dmraid FakeRAID

PCI Silicon Image 3512 RAID Controller.

00:0c.0 RAID bus controller: Silicon Image, Inc. SiI 3512 [SATALink/SATARaid] Serial ATA Controller (rev 01)

2 x Maxtor 6V160E0 Rev: VA13 SATA disks. (160gb each)

root@ultra:~# df -k
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/mapper/sil_agbheaaedgdc1 304397776 8813680 280121536 4% /

Setup B : Linux Software RAID

VT8237A SATA onboard controller with RAID off

00:0f.0 IDE interface: VIA Technologies, Inc. VT8237A SATA 2-Port Controller (rev 80)

2 x SAMSUNG HD160JJ Rev: ZM10 SATA disks. (160gb each)

root@ultra:~# df -k
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/md0 303765224 1848008 286486800 1% /

Benchmark Results

hdparm

dmraid [ 102.89 MB/sec ]

root@ultra:~# hdparm -tT /dev/mapper/sil_agbheaaedgdc1

/dev/mapper/sil_agbheaaedgdc1:
Timing cached reads: 3248 MB in 2.00 seconds = 1623.42 MB/sec
Timing buffered disk reads: 310 MB in 3.01 seconds = 102.89 MB/sec

Software RAID [ 118.28 MB/sec ]

root@ultra:~# hdparm -tT /dev/md0

/dev/md0:
Timing cached reads: 3284 MB in 2.00 seconds = 1642.35 MB/sec
Timing buffered disk reads: 356 MB in 3.01 seconds = 118.28 MB/sec

bonnie

dmraid [ 92204 K/sec ]

shaf@ultra:~$ bonnie
Version 1.03

Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP
ultra 2G 38388 97 92204 31 34184 11 30460 69 84613 16 167.4 0

Software RAID [ 114909 K/sec ]

shaf@ultra:~$ bonnie
Version 1.03

Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP
ultra 2G 50805 97 114909 29 40225 9 45872 82 99841 13 245.6 0

bootchart

dmraid [ 33 seconds to boot ] (Click to enlarge)

Software RAID [ 20 seconds to boot ] (Click to enlarge)

Conclusion

Although the bootchart results are somewhat skewed I would still have to say unequivocally that Linux Software RAID has grabbed my attention over FRAID.

This entry was posted on Saturday, March 31st, 2007 at 12:01 am and is filed under Computing, Linux. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.