From owner-freebsd-questions@freebsd.org Tue Apr 19 18:27:38 2016 Return-Path: Delivered-To: freebsd-questions@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id B7B77B15F9D for ; Tue, 19 Apr 2016 18:27:38 +0000 (UTC) (envelope-from jon@radel.com) Received: from radel.com (fly.radel.com [70.184.242.170]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client CN "*.radel.com", Issuer "COMODO RSA Domain Validation Secure Server CA" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 66F5C1EEF for ; Tue, 19 Apr 2016 18:27:37 +0000 (UTC) (envelope-from jon@radel.com) X-CGP-ClamAV-Result: CLEAN X-VirusScanner: Niversoft's CGPClamav Helper v1.18.7 (ClamAV engine v0.98.7) Received: from [2001:470:880a:4389:cd3f:351a:239d:ef64] (account jon@radel.com HELO gravenstein.local) by radel.com (CommuniGate Pro SMTP 6.1.2 _community_) with ESMTPSA id 1039384; Tue, 19 Apr 2016 17:27:28 +0000 Subject: Re: Raid 1+0 To: galtsev@kicp.uchicago.edu References: <571533F4.8040406@bananmonarki.se> <57153E6B.6090200@gmail.com> <20160418210257.GB86917@neutralgood.org> <64031.128.135.52.6.1461017122.squirrel@cosmo.uchicago.edu> <441t61efpv.fsf@be-well.ilk.org> <13260.128.135.52.6.1461084740.squirrel@cosmo.uchicago.edu> Cc: freebsd-questions@freebsd.org From: Jon Radel Message-ID: <57166A7F.2030104@radel.com> Date: Tue, 19 Apr 2016 13:27:27 -0400 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:38.0) Gecko/20100101 Thunderbird/38.7.2 MIME-Version: 1.0 In-Reply-To: <13260.128.135.52.6.1461084740.squirrel@cosmo.uchicago.edu> Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha-256; boundary="------------ms030207010000000203090407" X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 19 Apr 2016 18:27:38 -0000 This is a cryptographically signed message in MIME format. --------------ms030207010000000203090407 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: quoted-printable On 4/19/16 12:52 PM, Valeri Galtsev wrote: > Correct, we didn't hear proof of one or another. I, however, can not th= ink > of any physical mechanism that can be involved which will lead in case = of > failure of one drive to failure of another. That is why I assume events= > are (pretty much) independent. > > Personally I think you're thinking about it all wrong. I didn't catch=20 anyone claiming that failure of one drive caused the failure of another=20 (though I've not slogged through the whole thread). Only that failure=20 of drives from the same manufacturing batch have a tendency to have=20 similar lifespans, and therefore there is some correlation as to when=20 they die. They have the same design flaws. They have the same=20 substandard components. Etc., etc. Why do you think that drives=20 come with MTBF figures, and that they're not all the same for every=20 drive? That's the summary output of somebody's best estimation of the=20 failure curve for that particular model. Personally I've never had a clear cut example with disk drives, though I = did own enough 750 mb drives from brand X some years ago to learn that=20 the involved mechanism, on average, sucked compared to other brand X=20 drives, and they were not to be trusted long term. However, I once saw=20 this very clearly in LCD monitors where I had multiples of the same=20 model. Turns out that they were caught up in the big "counterfeit"=20 capacitor scandal way back when, when due to imperfect industrial=20 espionage, a manufacturer only thought they'd stolen the formula for a=20 nice electrolyte. Turns out there was one little factor they'd missed,=20 the stabilizer that kept the capacitor from dropping dead at pretty much = the same age as every other capacitor of that model. There most=20 certainly was correlation on those monitors failing. Luckily they were=20 all still in warranty. :-) --Jon Radel jon@radel.com --------------ms030207010000000203090407 Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="smime.p7s" Content-Description: S/MIME Cryptographic Signature MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCC Cq8wggSvMIIDl6ADAgECAhEA4CPLFRKDU4mtYW56VGdrITANBgkqhkiG9w0BAQsFADBvMQsw CQYDVQQGEwJTRTEUMBIGA1UEChMLQWRkVHJ1c3QgQUIxJjAkBgNVBAsTHUFkZFRydXN0IEV4 dGVybmFsIFRUUCBOZXR3b3JrMSIwIAYDVQQDExlBZGRUcnVzdCBFeHRlcm5hbCBDQSBSb290 MB4XDTE0MTIyMjAwMDAwMFoXDTIwMDUzMDEwNDgzOFowgZsxCzAJBgNVBAYTAkdCMRswGQYD VQQIExJHcmVhdGVyIE1hbmNoZXN0ZXIxEDAOBgNVBAcTB1NhbGZvcmQxGjAYBgNVBAoTEUNP TU9ETyBDQSBMaW1pdGVkMUEwPwYDVQQDEzhDT01PRE8gU0hBLTI1NiBDbGllbnQgQXV0aGVu dGljYXRpb24gYW5kIFNlY3VyZSBFbWFpbCBDQTCCASIwDQYJKoZIhvcNAQEBBQADggEPADCC AQoCggEBAImxDdp6UxlOcFIdvFamBia3uEngludRq/HwWhNJFaO0jBtgvHpRQqd5jKQi3xdh TpHVdiMKFNNKAn+2HQmAbqUEPdm6uxb+oYepLkNSQxZ8rzJQyKZPWukI2M+TJZx7iOgwZOak +FaA/SokFDMXmaxE5WmLo0YGS8Iz1OlAnwawsayTQLm1CJM6nCpToxDbPSBhPFUDjtlOdiUC ISn6o3xxdk/u4V+B6ftUgNvDezVSt4TeIj0sMC0xf1m9UjewM2ktQ+v61qXxl3dnUYzZ7ifr vKUHOHaMpKk4/9+M9QOsSb7K93OZOg8yq5yVOhM9DkY6V3RhUL7GQD/L5OKfoiECAwEAAaOC ARcwggETMB8GA1UdIwQYMBaAFK29mHo0tCb3+sQmVO8DveAky1QaMB0GA1UdDgQWBBSSYWuC 4aKgqk/sZ/HCo/e0gADB7DAOBgNVHQ8BAf8EBAMCAYYwEgYDVR0TAQH/BAgwBgEB/wIBADAd BgNVHSUEFjAUBggrBgEFBQcDAgYIKwYBBQUHAwQwEQYDVR0gBAowCDAGBgRVHSAAMEQGA1Ud HwQ9MDswOaA3oDWGM2h0dHA6Ly9jcmwudXNlcnRydXN0LmNvbS9BZGRUcnVzdEV4dGVybmFs Q0FSb290LmNybDA1BggrBgEFBQcBAQQpMCcwJQYIKwYBBQUHMAGGGWh0dHA6Ly9vY3NwLnVz ZXJ0cnVzdC5jb20wDQYJKoZIhvcNAQELBQADggEBABsqbqxVwTqriMXY7c1V86prYSvACRAj mQ/FZmpvsfW0tXdeDwJhAN99Bf4Ss6SAgAD8+x1banICCkG8BbrBWNUmwurVTYT7/oKYz1gb 4yJjnFL4uwU2q31Ypd6rO2Pl2tVz7+zg+3vio//wQiOcyraNTT7kSxgDsqgt1Ni7QkuQaYUQ 26Y3NOh74AEQpZzKOsefT4g0bopl0BqKu6ncyso20fT8wmQpNa/WsadxEdIDQ7GPPprsnjJT 9HaSyoY0B7ksyuYcStiZDcGG4pCS+1pCaiMhEOllx/XVu37qjIUgAmLq0ToHLFnFmTPyOInl tukWeh95FPZKEBom+nyK+5swggX4MIIE4KADAgECAhBzVOU8fWu0zQ1gaQ38zgEbMA0GCSqG SIb3DQEBCwUAMIGbMQswCQYDVQQGEwJHQjEbMBkGA1UECBMSR3JlYXRlciBNYW5jaGVzdGVy MRAwDgYDVQQHEwdTYWxmb3JkMRowGAYDVQQKExFDT01PRE8gQ0EgTGltaXRlZDFBMD8GA1UE AxM4Q09NT0RPIFNIQS0yNTYgQ2xpZW50IEF1dGhlbnRpY2F0aW9uIGFuZCBTZWN1cmUgRW1h aWwgQ0EwHhcNMTUwMzMwMDAwMDAwWhcNMTgwMzI5MjM1OTU5WjCB+jELMAkGA1UEBhMCVVMx DjAMBgNVBBETBTIyMTUwMQswCQYDVQQIEwJWQTEUMBIGA1UEBxMLU3ByaW5nZmllbGQxGjAY BgNVBAkTETY5MTcgUmlkZ2V3YXkgRHIuMRUwEwYDVQQKEwxKb24gVC4gUmFkZWwxMjAwBgNV BAsTKUlzc3VlZCB0aHJvdWdoIEpvbiBULiBSYWRlbCBFLVBLSSBNYW5hZ2VyMR8wHQYDVQQL ExZDb3Jwb3JhdGUgU2VjdXJlIEVtYWlsMRIwEAYDVQQDEwlKb24gUmFkZWwxHDAaBgkqhkiG 9w0BCQEWDWpvbkByYWRlbC5jb20wggEiMA0GCSqGSIb3DQEBAQUAA4IBDwAwggEKAoIBAQDe 1Rth9hbQqaODn++C5dVAQH9nM2VH3oPazZufOwmIG2SXI/v3PuemcQQ3JkhmpQ06gYszyXbk TCLsqvEfalYj81jdt/K5lT4aVdj0LfJIWyTcU95V2rsCuHsSvn/PnIcsEtXg53rCtqS4EOtJ 9u3rY2hP8YCiyz1yY3mn4nKJs93MHG4AkXYuVpzfaIADETcVrA+razvXEfnDJXXDZZ9ZuuV1 06yIovOvhYWSlaVu8nrSHJjXFZI2IXwgIeVBoMih3yu6LLj14I/YdZ0rIA8K+UNB+NW6Ri3u wHXBbr4jh3ZqkrqIVUrf1VeybhdrJcdqXdMNHjKDSlCoaxYRbLy1AgMBAAGjggHVMIIB0TAf BgNVHSMEGDAWgBSSYWuC4aKgqk/sZ/HCo/e0gADB7DAdBgNVHQ4EFgQUz9YB10WEfBNHskRw o/0vh8qaQuwwDgYDVR0PAQH/BAQDAgWgMAwGA1UdEwEB/wQCMAAwHQYDVR0lBBYwFAYIKwYB BQUHAwQGCCsGAQUFBwMCMEYGA1UdIAQ/MD0wOwYMKwYBBAGyMQECAQMFMCswKQYIKwYBBQUH AgEWHWh0dHBzOi8vc2VjdXJlLmNvbW9kby5uZXQvQ1BTMF0GA1UdHwRWMFQwUqBQoE6GTGh0 dHA6Ly9jcmwuY29tb2RvY2EuY29tL0NPTU9ET1NIQTI1NkNsaWVudEF1dGhlbnRpY2F0aW9u YW5kU2VjdXJlRW1haWxDQS5jcmwwgZAGCCsGAQUFBwEBBIGDMIGAMFgGCCsGAQUFBzAChkxo dHRwOi8vY3J0LmNvbW9kb2NhLmNvbS9DT01PRE9TSEEyNTZDbGllbnRBdXRoZW50aWNhdGlv bmFuZFNlY3VyZUVtYWlsQ0EuY3J0MCQGCCsGAQUFBzABhhhodHRwOi8vb2NzcC5jb21vZG9j YS5jb20wGAYDVR0RBBEwD4ENam9uQHJhZGVsLmNvbTANBgkqhkiG9w0BAQsFAAOCAQEAS1Pe +gBgP+SQ/a5I5e7zX0Rg0DhH378LHlZixJgS6LfCPL2edKMUQi3Th9GXfLjdeyeWuMWoz925 ZzBHcPwkBeH+iM/AEhu0Dhi0kop/p66g9tEPJUZ/KDsqxddNDrD0Typn3/33pHTjJEDqydzA gwB0Nn8blpMbqSwT+j8wuPakfLsj1cSDzXrTLLsmIQB7auAyaYXdWyW8Yqw336rLUCvjOUfn qOOyjVsieTw/0PLoOHJaGyez+VtV4eyi6p1SNiX32A+fvxBMzKQLCokE43cXItc9Okzq//f2 fuvGp17r8mpm4OjjM5E2kwsg9bBPUBMR4/sxosKVLn0o9rxlozGCBEEwggQ9AgEBMIGwMIGb MQswCQYDVQQGEwJHQjEbMBkGA1UECBMSR3JlYXRlciBNYW5jaGVzdGVyMRAwDgYDVQQHEwdT YWxmb3JkMRowGAYDVQQKExFDT01PRE8gQ0EgTGltaXRlZDFBMD8GA1UEAxM4Q09NT0RPIFNI QS0yNTYgQ2xpZW50IEF1dGhlbnRpY2F0aW9uIGFuZCBTZWN1cmUgRW1haWwgQ0ECEHNU5Tx9 a7TNDWBpDfzOARswDQYJYIZIAWUDBAIBBQCgggJhMBgGCSqGSIb3DQEJAzELBgkqhkiG9w0B BwEwHAYJKoZIhvcNAQkFMQ8XDTE2MDQxOTE3MjcyN1owLwYJKoZIhvcNAQkEMSIEILL6hXbP /x4SMVSGEjjcyRw0ic/hYunan9RB8fK9OT+RMGwGCSqGSIb3DQEJDzFfMF0wCwYJYIZIAWUD BAEqMAsGCWCGSAFlAwQBAjAKBggqhkiG9w0DBzAOBggqhkiG9w0DAgICAIAwDQYIKoZIhvcN AwICAUAwBwYFKw4DAgcwDQYIKoZIhvcNAwICASgwgcEGCSsGAQQBgjcQBDGBszCBsDCBmzEL MAkGA1UEBhMCR0IxGzAZBgNVBAgTEkdyZWF0ZXIgTWFuY2hlc3RlcjEQMA4GA1UEBxMHU2Fs Zm9yZDEaMBgGA1UEChMRQ09NT0RPIENBIExpbWl0ZWQxQTA/BgNVBAMTOENPTU9ETyBTSEEt MjU2IENsaWVudCBBdXRoZW50aWNhdGlvbiBhbmQgU2VjdXJlIEVtYWlsIENBAhBzVOU8fWu0 zQ1gaQ38zgEbMIHDBgsqhkiG9w0BCRACCzGBs6CBsDCBmzELMAkGA1UEBhMCR0IxGzAZBgNV BAgTEkdyZWF0ZXIgTWFuY2hlc3RlcjEQMA4GA1UEBxMHU2FsZm9yZDEaMBgGA1UEChMRQ09N T0RPIENBIExpbWl0ZWQxQTA/BgNVBAMTOENPTU9ETyBTSEEtMjU2IENsaWVudCBBdXRoZW50 aWNhdGlvbiBhbmQgU2VjdXJlIEVtYWlsIENBAhBzVOU8fWu0zQ1gaQ38zgEbMA0GCSqGSIb3 DQEBAQUABIIBAGfOuB1PGkdr6lsTZhTzhWtWQslOYLnAKCe+YP6VP72zBJQohLb5GL0Y/U2K GTo9nvnDCW2052q4kG09snTVy6vUZo8/rP0E+HMkktUM9ojABILmOd8bbpvL+3rTEe+JAcM7 Abfpi2/VTUsxv7GLKfl+hDr/lyaoeKkaP+uZD9XfC1gHDGj8Jlsixejd1KuTOxj3Knp3lTdz Bow4df1P7JZ4yyAB2kzDlnSayZYGXymcnP45sivxQZN2bMDqcYj3BQUMFWewKZHehcQXmozQ SPLzz9mFtB/4dfjWWqlPGHOUIfwpPezCGj9JL0K8qMgW0Mssat+pwPQ8r6XloS/gdVwAAAAA AAA= --------------ms030207010000000203090407--