From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?UTF-8?Q?Mathias_Bur=C3=A9n?= Subject: Re: Performance question, RAID5 Date: Sun, 30 Jan 2011 00:27:22 +0000 Message-ID: References: <20110130035352.1d72e8d1@natsu> <20110130045706.4e8d6fa2@natsu> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <20110130045706.4e8d6fa2@natsu> Sender: linux-raid-owner@vger.kernel.org To: Roman Mamedov Cc: Linux-RAID List-Id: linux-raid.ids On 29 January 2011 23:57, Roman Mamedov wrote: > On Sat, 29 Jan 2011 23:44:01 +0000 > Mathias Bur=C3=A9n wrote: > >> Controller device @ pci0000:00/0000:00:16.0/0000:05:00.0 [sata_mv] >> =C2=A0 SCSI storage controller: HighPoint Technologies, Inc. RocketR= AID >> 230x 4 Port SATA-II Controller (rev 02) >> =C2=A0 =C2=A0 host6: [Empty] >> =C2=A0 =C2=A0 host7: /dev/sde ATA SAMSUNG HD204UI {SN: S2HGJ1RZ80096= 4 } >> =C2=A0 =C2=A0 host8: /dev/sdf ATA WDC WD20EARS-00M {SN: WD-WCAZA1000= 331} >> =C2=A0 =C2=A0 host9: /dev/sdg ATA SAMSUNG HD204UI {SN: S2HGJ1RZ80085= 0 } > > Does this controller support PCI-E 2.0? I doubt it. > Does you Atom mainboard support PCI-E 2.0? I highly doubt it. > And if PCI-E 1.0/1.1 is used, these last 3 drives are limited to 250 = MB/sec. > in total, which in reality will be closer to 200 MB/sec. > >> It's all SATA 3Gbs. OK, so from what you're saying I should see >> significantly better results on a better CPU? The HDDs should be abl= e >> to push 80MB/s (read or write), and that should yield at least 5*80 = =3D >> 400MB/s (-1 for parity) on easy (sequential?) reads. > > According to the hdparm benchmark, your CPU can not read faster than = 640 > MB/sec from _RAM_, and that's just plain easy linear data from a buff= er. So it > is perhaps not promising with regard to whether you will get 400MB/se= c reading > from RAID6 (with all the corresponding overheads) or not. > > -- > With respect, > Roman > Ah, right. The Ion platform actually supports PCI-E 2.0, but the controller I'm using doesn't, according to lspci, if I understand it correctly. SATA ontroller: 05:00.0 SCSI storage controller: HighPoint Technologies, Inc. RocketRAID 230x 4 Port SATA-II Controller (rev 02) Subsystem: Marvell Technology Group Ltd. Device 11ab [....] Capabilities: [60] Express (v1) Legacy Endpoint, MSI 00 PCI-Express bridge: 00:18.0 PCI bridge: nVidia Corporation MCP79 PCI Express Bridge (rev b1) (prog-if 00 [Normal decode]) Control: I/O- Mem- BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx- [...] Capabilities: [80] Express (v2) Root Port (Slot+), MSI 00 That might explain why the different stripe caches didn't have any effect either. Thanks for pointing that out, apparently I didn't think about it when I purchased the (super cheap) card. // Mathias -- To unsubscribe from this list: send the line "unsubscribe linux-raid" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html