From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pieter De Wit Subject: Re: Is partition alignment needed for RAID partitions ? Date: Tue, 31 Dec 2013 07:32:26 +1300 Message-ID: <52C1BC3A.3070106@insync.za.net> References: <52C08E63.8020800@insync.za.net> <52C11929.3070600@hardwarefreak.com> <52C12F8B.6080507@insync.za.net> <52C14FB8.8080005@hardwarefreak.com> <52C162A7.1080309@insync.za.net> <52C1A8F0.2030208@hardwarefreak.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <52C1A8F0.2030208@hardwarefreak.com> Sender: linux-raid-owner@vger.kernel.org To: stan@hardwarefreak.com, linux-raid List-Id: linux-raid.ids Hi Stan, > (3407028224 sectors * 512 bytes per sector) / 524288 (chunk bytes) = > > 3327176 chunks Right - more for clarity, these are the 512 byte sectors, not the 4k ones (otherwise I would have had a 12 TB drive :) ) > Please show the exact iostat command line you are using and the output. iostat -x 1 >> Also, there is no other disk usage in the system. All the data is >> currently on the NAS (except system "stuff" for a quite firewall) >> >> I just spotted another thing, the two drives are on the same SATA >> controller, from rescan-scsi-bus: >> >> Scanning for device 3 0 0 0 ... >> OLD: Host: scsi3 Channel: 00 Id: 00 Lun: 00 >> Vendor: ATA Model: WDC WD20EARX-008 Rev: 51.0 >> Type: Direct-Access ANSI SCSI revision: 05 >> Scanning for device 3 0 1 0 ... >> OLD: Host: scsi3 Channel: 00 Id: 01 Lun: 00 >> Vendor: ATA Model: WDC WD20EARX-008 Rev: 51.0 >> Type: Direct-Access ANSI SCSI revision: 05 >> >> Would it be better to move these apart ? I remember IDE used to have >> this issue, but I also recall SATA "fixed" that. > This isn't the problem. Even if both drives were connected via a plain > old 33MHz 132MB/s PCI SATA card you'd still be capable of 120MB/s > throughput, 60MB/s per drive. > >> Thanks again, > You're welcome. Eventually you get to the bottom of this. And the email :) I now have the drive with no data on them, so I can even run write tests. I am going to start with the usual "dd" tests, any other that you would like to see ? Cheers, Pieter