From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ig0-f178.google.com ([209.85.213.178]:33572 "EHLO mail-ig0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161865AbbKTN35 (ORCPT ); Fri, 20 Nov 2015 08:29:57 -0500 Received: by igvi2 with SMTP id i2so32777496igv.0 for ; Fri, 20 Nov 2015 05:29:57 -0800 (PST) Subject: Re: Self-destruct of btrfs RAID6 array To: Paul Loewenstein , linux-btrfs@vger.kernel.org References: <564E9D62.4050306@gmail.com> From: Austin S Hemmelgarn Message-ID: <564F2047.5010508@gmail.com> Date: Fri, 20 Nov 2015 08:29:43 -0500 MIME-Version: 1.0 In-Reply-To: <564E9D62.4050306@gmail.com> Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha-512; boundary="------------ms050606090103050303060807" Sender: linux-btrfs-owner@vger.kernel.org List-ID: This is a cryptographically signed message in MIME format. --------------ms050606090103050303060807 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable On 2015-11-19 23:11, Paul Loewenstein wrote: > I have just had an apparently catastrophic collapse of a large RAID6 > array. I was hoping that the dual-redundancy of a RAID6 array would > compensate for having no backup media large enough to back it up! Duncan already did a really good job of explaining this (and from what I = can tell, I'm pretty sure his analysis of what's going on is correct),=20 but I would like to add a couple of things. First, RAID is not a backup, it's a way to minimize the need to restore=20 from backups in the event of hardware failure (or, in the case of BTRFS, = also a way to minimize the effects of data corruption). Second, have you considered doing encrypted backups to a cloud storage=20 service? This is what I personally do, and it works really well for me. = Amazon S3 has pretty reasonable pricing, and there are multiple=20 options on Linux to allow accessing it like a filesystem. There are=20 many other options as well (in my case, I backup to both S3 and Dropbox, = but I also have small enough backups that I don't need to worry about=20 the 1T limit on Dropbox for non-business accounts). --------------ms050606090103050303060807 Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="smime.p7s" Content-Description: S/MIME Cryptographic Signature MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgMFADCABgkqhkiG9w0BBwEAAKCC Brgwgga0MIIEnKADAgECAgMRLfgwDQYJKoZIhvcNAQENBQAweTEQMA4GA1UEChMHUm9vdCBD QTEeMBwGA1UECxMVaHR0cDovL3d3dy5jYWNlcnQub3JnMSIwIAYDVQQDExlDQSBDZXJ0IFNp Z25pbmcgQXV0aG9yaXR5MSEwHwYJKoZIhvcNAQkBFhJzdXBwb3J0QGNhY2VydC5vcmcwHhcN MTUwOTIxMTEzNTEzWhcNMTYwMzE5MTEzNTEzWjBjMRgwFgYDVQQDEw9DQWNlcnQgV29UIFVz ZXIxIzAhBgkqhkiG9w0BCQEWFGFoZmVycm9pbjdAZ21haWwuY29tMSIwIAYJKoZIhvcNAQkB FhNhaGVtbWVsZ0BvaGlvZ3QuY29tMIICIjANBgkqhkiG9w0BAQEFAAOCAg8AMIICCgKCAgEA nQ/81tq0QBQi5w316VsVNfjg6kVVIMx760TuwA1MUaNQgQ3NyUl+UyFtjhpkNwwChjgAqfGd LIMTHAdObcwGfzO5uI2o1a8MHVQna8FRsU3QGouysIOGQlX8jFYXMKPEdnlt0GoQcd+BtESr pivbGWUEkPs1CwM6WOrs+09bAJP3qzKIr0VxervFrzrC5Dg9Rf18r9WXHElBuWHg4GYHNJ2V Ab8iKc10h44FnqxZK8RDN8ts/xX93i9bIBmHnFfyNRfiOUtNVeynJbf6kVtdHP+CRBkXCNRZ qyQT7gbTGD24P92PS2UTmDfplSBcWcTn65o3xWfesbf02jF6PL3BCrVnDRI4RgYxG3zFBJuG qvMoEODLhHKSXPAyQhwZINigZNdw5G1NqjXqUw+lIqdQvoPijK9J3eijiakh9u2bjWOMaleI SMRR6XsdM2O5qun1dqOrCgRkM0XSNtBQ2JjY7CycIx+qifJWsRaYWZz0aQU4ZrtAI7gVhO9h pyNaAGjvm7PdjEBiXq57e4QcgpwzvNlv8pG1c/hnt0msfDWNJtl3b6elhQ2Pz4w/QnWifZ8E BrFEmjeeJa2dqjE3giPVWrsH+lOvQQONsYJOuVb8b0zao4vrWeGmW2q2e3pdv0Axzm/60cJQ haZUv8+JdX9ZzqxOm5w5eUQSclt84u+D+hsCAwEAAaOCAVkwggFVMAwGA1UdEwEB/wQCMAAw VgYJYIZIAYb4QgENBEkWR1RvIGdldCB5b3VyIG93biBjZXJ0aWZpY2F0ZSBmb3IgRlJFRSBo ZWFkIG92ZXIgdG8gaHR0cDovL3d3dy5DQWNlcnQub3JnMA4GA1UdDwEB/wQEAwIDqDBABgNV HSUEOTA3BggrBgEFBQcDBAYIKwYBBQUHAwIGCisGAQQBgjcKAwQGCisGAQQBgjcKAwMGCWCG SAGG+EIEATAyBggrBgEFBQcBAQQmMCQwIgYIKwYBBQUHMAGGFmh0dHA6Ly9vY3NwLmNhY2Vy dC5vcmcwMQYDVR0fBCowKDAmoCSgIoYgaHR0cDovL2NybC5jYWNlcnQub3JnL3Jldm9rZS5j cmwwNAYDVR0RBC0wK4EUYWhmZXJyb2luN0BnbWFpbC5jb22BE2FoZW1tZWxnQG9oaW9ndC5j b20wDQYJKoZIhvcNAQENBQADggIBADMnxtSLiIunh/TQcjnRdf63yf2D8jMtYUm4yDoCF++J jCXbPQBGrpCEHztlNSGIkF3PH7ohKZvlqF4XePWxpY9dkr/pNyCF1PRkwxUURqvuHXbu8Lwn 8D3U2HeOEU3KmrfEo65DcbanJCMTTW7+mU9lZICPP7ZA9/zB+L0Gm1UNFZ6AU50N/86vjQfY WgkCd6dZD4rQ5y8L+d/lRbJW7ZGEQw1bSFVTRpkxxDTOwXH4/GpQfnfqTAtQuJ1CsKT12e+H NSD/RUWGTr289dA3P4nunBlz7qfvKamxPymHeBEUcuICKkL9/OZrnuYnGROFwcdvfjGE5iLB kjp/ttrY4aaVW5EsLASNgiRmA6mbgEAMlw3RwVx0sVelbiIAJg9Twzk4Ct6U9uBKiJ8S0sS2 8RCSyTmCRhJs0vvva5W9QUFGmp5kyFQEoSfBRJlbZfGX2ehI2Hi3U2/PMUm2ONuQG1E+a0AP u7I0NJc/Xil7rqR0gdbfkbWp0a+8dAvaM6J00aIcNo+HkcQkUgtfrw+C2Oyl3q8IjivGXZqT 5UdGUb2KujLjqjG91Dun3/RJ/qgQlotH7WkVBs7YJVTCxfkdN36rToPcnMYOI30FWa0Q06gn F6gUv9/mo6riv3A5bem/BdbgaJoPnWQD9D8wSyci9G4LKC+HQAMdLmGoeZfpJzKHMYIE0TCC BM0CAQEwgYAweTEQMA4GA1UEChMHUm9vdCBDQTEeMBwGA1UECxMVaHR0cDovL3d3dy5jYWNl cnQub3JnMSIwIAYDVQQDExlDQSBDZXJ0IFNpZ25pbmcgQXV0aG9yaXR5MSEwHwYJKoZIhvcN AQkBFhJzdXBwb3J0QGNhY2VydC5vcmcCAxEt+DANBglghkgBZQMEAgMFAKCCAiEwGAYJKoZI hvcNAQkDMQsGCSqGSIb3DQEHATAcBgkqhkiG9w0BCQUxDxcNMTUxMTIwMTMyOTQzWjBPBgkq hkiG9w0BCQQxQgRAh5QSO/4HkndU3VtFuW1LtC5CGbd/v+xCVeThm08Fs8FxfmbeCD77z0z0 lLN4bKP89eQDZvUP1GnH+9F5ULSsZjBsBgkqhkiG9w0BCQ8xXzBdMAsGCWCGSAFlAwQBKjAL BglghkgBZQMEAQIwCgYIKoZIhvcNAwcwDgYIKoZIhvcNAwICAgCAMA0GCCqGSIb3DQMCAgFA MAcGBSsOAwIHMA0GCCqGSIb3DQMCAgEoMIGRBgkrBgEEAYI3EAQxgYMwgYAweTEQMA4GA1UE ChMHUm9vdCBDQTEeMBwGA1UECxMVaHR0cDovL3d3dy5jYWNlcnQub3JnMSIwIAYDVQQDExlD QSBDZXJ0IFNpZ25pbmcgQXV0aG9yaXR5MSEwHwYJKoZIhvcNAQkBFhJzdXBwb3J0QGNhY2Vy dC5vcmcCAxEt+DCBkwYLKoZIhvcNAQkQAgsxgYOggYAweTEQMA4GA1UEChMHUm9vdCBDQTEe MBwGA1UECxMVaHR0cDovL3d3dy5jYWNlcnQub3JnMSIwIAYDVQQDExlDQSBDZXJ0IFNpZ25p bmcgQXV0aG9yaXR5MSEwHwYJKoZIhvcNAQkBFhJzdXBwb3J0QGNhY2VydC5vcmcCAxEt+DAN BgkqhkiG9w0BAQEFAASCAgCUneAyLrwtQzIm6R/wuM6D+MM/CZiadNHwWpnOSWLWq/O+hT3T /I7j9tD2VloUyOEVNRUaAGLKbDYw50feF5Xbs2E7wE7QItGd7PGIeFJGjv+ucBzhQl0KQ/QW 45pph6AClZuDFEU+PFka0r6XFT2DE17kz19B7Ze2S1gkmLclDW1yEQHYDXCVKPbfcqsPgY/2 sTBgae6QzyKp3X56eFTxclhzlAe3aNVcuBQ5B+9n/8j5BQGXJN1+LY0XABm3igLGn1hIlkL7 HvthBVH5K/B+01hu4OCBKi9w4RuJ2tWwrB8xF0jlDKAePB1BufNfvnPWV7GPpTihsBTI5YWL CgjkEKj/69IY4+4aOS98uamXYEv1b7KkXqec6J600SNKiZ+tkDSOyI0JYD4NRC4OgglTRRLK ndoG3Nh7HdAIT/N3xJbuOAQ75JzHMv3+PDAQ2QQk1vfw6YUarn0IeQX80BNqkEEMthniXz6t IdpbUlmC3QlmbTQr+rtfMlGTpyswmehVNRUuHC/DDzRcy+a7DLQXslKIuDggK3XqqQEY67ql TdEKH7i9MfS1GDDpxAb8w4ePNSWCGV2NU5do7mYrQf2jFX4uwotV/QByJA0j5lrQFasgErQN SaC1oJnPe9sxoPBjun9EUqFR+3Rde0+j0gYUsGNmEfY80zyJFGO8TPa8SgAAAAAAAA== --------------ms050606090103050303060807--