From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Evans Subject: Re: Typical RAID5 transfer speeds Date: Sat, 19 Dec 2009 20:21:50 -0800 Message-ID: <4877c76c0912192021s2c3da63au57f5dcb0391b3eb3@mail.gmail.com> References: <4B2D4731.3090702@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <4B2D4731.3090702@gmail.com> Sender: linux-raid-owner@vger.kernel.org To: Roger Heflin Cc: Matt Tehonica , linux-raid@vger.kernel.org List-Id: linux-raid.ids On Sat, Dec 19, 2009 at 1:35 PM, Roger Heflin w= rote: > Matt Tehonica wrote: >> >> I have a 4 disk RAID5 using a 2048K chunk size and using XFS filesys= tem. >> =A0Typical file size is about 2GB-5GB. I usually get around 50MB/sec= transfer >> speed when writting files to the array. Is this typcial or is it bel= ow >> normal? =A0A friend has a 20 disk RAID6 using the same filesystem an= d chunk >> size and gets around 150MB/sec. Any input on this?? >> >> Thanks, >> Matt > > Speed depends on how the disks are connected to the system, and how m= any > disks there are per connection, and what kind of disks they are. > > If your friend had a 20 disk raid6 on one 4port sata pci-32bit/33mhz = card > with port multipliers his total throughput would be <110mb/second rea= ds or > writes, if your friend had 20 disks on 10+ port pcie-x16 cards his to= tal > possible speed would be much much higher, reads would be expected to = be > 18x(rawdiskrate) if the machine could handle it. > > Also newer disks are faster than older disks. > > 1.5tb disks read/write at 125-130+ MB/second on a fast port. > 1.5tb disks read/write at 75-80 MB/second on a PCI-32bit/33mhz port. > 500gb disks read/write at 75-80 MB/second on a PCI-32bit/33mhz port. > 250gb disks read/write at 50-55 MB/second on a fast port. > > And those PCI-32bit/33mhz ports are with only a single disk, put more= than > one on there, and the io rates drop...so 2 disk on pci-32bit/33mhz (o= ld PCI) > port will have <50MB/second each no matter how fast the disk is, put = 3 on > there and each disk is down to 33mhz, 4 25MB/second or less. > -- > To unsubscribe from this list: send the line "unsubscribe linux-raid"= in > the body of a message to majordomo@vger.kernel.org > More majordomo info at =A0http://vger.kernel.org/majordomo-info.html > Speaking of 16x 16 port cards, why is it that it's so difficult to find an 8 or 16 port 4 or 8/16x pcie adapter? A good 1xpci-e to 2x SATA costs like 25 to 50 USD. Given the reduction in duplicate components, it should not be hard to make a card with 8 ports for 100 USD or less right? I don't even want any intelligence, just normal disk to PCI-E lane connectin would be fine. -- 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