From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wolfgang Denk Subject: Re: Huge values of mismatch_cnt on RAID 6 arrays under Fedora 18 Date: Mon, 28 Jan 2013 07:43:32 +0100 Message-ID: <20130128064332.4E502258985@gemini.denx.de> References: <20130127192656.634892005AD@gemini.denx.de> <5105D0EA.7080100@turmel.org> <6BCDA3B1-C137-486D-A45D-55912207AF3C@colorremedies.com> <2C80C970-FE4F-4CFE-8F40-48BE14F3140F@colorremedies.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Return-path: In-reply-to: <2C80C970-FE4F-4CFE-8F40-48BE14F3140F@colorremedies.com> Sender: linux-raid-owner@vger.kernel.org To: Chris Murphy Cc: Phil Turmel , Brad Campbell , "linux-raid@vger.kernel.org Raid" List-Id: linux-raid.ids Dear Chris, In message <2C80C970-FE4F-4CFE-8F40-48BE14F3140F@colorremedies.com> you wrote: > > > The mismatch number is not divisible by 16, yet your chunk size is > 16KB. It is divisible by 4 and 8, so I'm going to guess that the > physical sector size is 4096 bytes. If correct, I'm coming up with a > maximum of 346GiB worth of sectors may be adversely affected, assuming > every sector in the mismatch count is bad (which is probably not true, > but could be). > > Since the upgrade to Fedora 18 for this particular RAID 6, can you > estimate how much data has been written to the array? Could it be in the > 90GiB to 350GiB range? No. Much less has been written. But then, your calculation above is wrong - these are 510 byte sector disks. > man 4 md says the same, for raid 5 and 6, mismatches are not expected to > be software problems, but much more likely hardware. But if it's true > that the OP's problems started exactly with the upgrade to Fedora 18, > that it could be a device driver. What HBA is being used? Correct, the hardware has not been changed, and has been running fine for many months before, Two of the systems use a Marvell Technology Group Ltd. MV88SX6081 8-port SATA II PCI-X Controller; the third system uses a LSI Logic / Symbios Logic SAS1068E PCI-Express Fusion-MPT SAS controller. Best regards, Wolfgang Denk -- DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd@denx.de Human beings were created by water to transport it uphill.