Date: Fri, 20 Aug 2004 21:35:47 +0200 From: Pawel Jakub Dawidek <pjd@FreeBSD.org> To: Greg 'groggy' Lehey <grog@FreeBSD.org> Cc: freebsd-performance@freebsd.org Subject: Re: RAID-3? (was: cvs commit: src MAINTAINERS) Message-ID: <20040820193547.GZ30151@darkness.comp.waw.pl> In-Reply-To: <20040819024359.GA85432@wantadilla.lemis.com> References: <20040817132740.GA32139@freebie.xs4all.nl> <41449.1092750244@critter.freebsd.dk> <200408161043.i7GAhfXs079045@repoman.freebsd.org> <20040817004407.GA81257@wantadilla.lemis.com> <20040817074633.GO30151@darkness.comp.waw.pl> <20040817112900.GA31635@freebie.xs4all.nl> <20040817124020.GK88156@wantadilla.lemis.com> <20040817131612.GT30151@darkness.comp.waw.pl> <20040819024359.GA85432@wantadilla.lemis.com>
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On Thu, Aug 19, 2004 at 12:13:59PM +0930, Greg 'groggy' Lehey wrote:
+> On Tuesday, 17 August 2004 at 15:16:12 +0200, Pawel Jakub Dawidek wrote:
+> > On Tue, Aug 17, 2004 at 10:10:20PM +0930, Greg 'groggy' Lehey wrote:
+> > +> On the contrary. RAID-3 requires byte-level striping, which is
+> > +> ridiculous on the hardware that FreeBSD supports.
[...]
+> > Want to compare performance with vinum's RAID5?:)
+>=20
+> Feel free. But do it with more than a single process accessing the
+> disks.
Tests were done using this HW:
CPU: Pentium II/Pentium II Xeon/Celeron (534.55-MHz 686-class CPU)
Origin =3D "GenuineIntel" Id =3D 0x665 Stepping =3D 5
Features=3D0x183fbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE=
,MCA,CMOV,PAT,PSE36,MMX,FXSR>
real memory =3D 67108864 (64 MB)
avail memory =3D 60256256 (57 MB)
MPTable: <OEM00000 PROD00000000>
FreeBSD/SMP: Multiprocessor System Detected: 2 CPUs
[...]
iir0: <ICP Disk Array Controller> mem 0xd8100000-0xd8103fff irq 17 at devic=
e 13.0 on pci0
[...]
da0 at iir0 bus 2 target 0 lun 0
da0: <ICP Host Drive #00 > Fixed Direct Access SCSI-2 device=20
da0: Tagged Queueing Enabled
da0: 8675MB (17767890 512 byte sectors: 255H 63S/T 1106C)
da1 at iir0 bus 2 target 1 lun 0
da1: <ICP Host Drive #01 > Fixed Direct Access SCSI-2 device=20
da1: Tagged Queueing Enabled
da1: 8675MB (17767890 512 byte sectors: 255H 63S/T 1106C)
da2 at iir0 bus 2 target 2 lun 0
da2: <ICP Host Drive #02 > Fixed Direct Access SCSI-2 device=20
da2: Tagged Queueing Enabled
da2: 8675MB (17767890 512 byte sectors: 255H 63S/T 1106C)
The software you can find under /usr/src/tools/tools/raidtest/ in HEAD
branch.
Test has been done for 10000 random requests (offset, size and operation
type was random).
RAID3:
Number of Bytes per Requests per
Operations processes second second
----------------------------------------------------------------------
READ 3 6329500 95
READ 15 8981047 135
READ 100 10719314 161
WRITE 3 5073263 76
WRITE 15 7467387 112
WRITE 100 8631136 129
READ/WRITE 3 6041795 90
READ/WRITE 15 8104847 121
READ/WRITE 100 9494250 142
RAID5:
Number of Bytes per Requests per
Operations processes second second
----------------------------------------------------------------------
READ 3 6041795 90
READ 15 14768833 222
READ 100 19546985 294
WRITE 3 3479568 52
WRITE 15 5403231 81
WRITE 100 6211191 93
READ/WRITE 3 4521071 68
READ/WRITE 15 7911875 119
READ/WRITE 100 9360528 140
As you can see RAID5 is only faster in READ tests for 15 and 100 processes
working in parallel. As I can see, RAID3 is faster in all the rest tests.
Of course you are welcome to try by yourself.
Anyway, if I can ask for something. Think twice before calling something
ridiculous without understanding.
PS. I wonder about read optimization, so parity component can be also
used for reading in round-robin fashion...
--=20
Pawel Jakub Dawidek http://www.FreeBSD.org
pjd@FreeBSD.org http://garage.freebsd.pl
FreeBSD committer Am I Evil? Yes, I Am!
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