From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f170.google.com ([209.85.223.170]:33812 "EHLO mail-io0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751585AbbJTMqJ (ORCPT ); Tue, 20 Oct 2015 08:46:09 -0400 Received: by iow1 with SMTP id 1so20280008iow.1 for ; Tue, 20 Oct 2015 05:46:08 -0700 (PDT) Subject: Re: N-Way (traditional) RAID-1 development status To: james harvey , linux-btrfs@vger.kernel.org References: From: Austin S Hemmelgarn Message-ID: <56263769.3030903@gmail.com> Date: Tue, 20 Oct 2015 08:45:29 -0400 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha-512; boundary="------------ms070409010700000709040405" Sender: linux-btrfs-owner@vger.kernel.org List-ID: This is a cryptographically signed message in MIME format. --------------ms070409010700000709040405 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable On 2015-10-19 23:13, james harvey wrote: > Wanted to see if there's active development on N-Way (traditional) RAID= -1. > > By this, I mean that RAID-1 across "n" disks traditionally means "n" > copies of data, but btrfs currently implements RAID-1 as "2" copies of > data. So, unlike traditional RAID-1, losing 2 drives in a many drive > array might cause data loss. It's been mentioned before that N-Way > (traditional) RAID-1 should eventually be implemented through btrfs. Before I go any further, I would like to point out that most traditional = hardware RAID controllers only support two disks for RAID-1=20 configurations, and the only one I've seen that doesn't does RAID-1 like = BTRFS (two copies total of each block). The whole 'RAID-1 on n disks is = n copies' thing actually started with Linux's MD-RAID subsystem, and=20 just happens to have been popular enough that other software RAID=20 implementations adopted those semantics as well. OK, with that historical rant out of the way, back to your actual=20 question: Based on what has been said in the past, N-way replication is = planned for development after the raid56 code is considered stable.=20 Based on that and past experience, I'd say to expect it no sooner than=20 4.8, or if we're _really_ lucky, 4.7. On top of that, based on past=20 experience with BTRFS\, I would not suggest actually trying it for=20 anything other than testing until at least one release after the initial = release. --------------ms070409010700000709040405 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 hvcNAQkDMQsGCSqGSIb3DQEHATAcBgkqhkiG9w0BCQUxDxcNMTUxMDIwMTI0NTI5WjBPBgkq hkiG9w0BCQQxQgRAuvrDYgk8IY3uACZUAoPxmfNayEGoOdDmdIJtdN5skvU88k4OCQ01ojbX 7N4XPSPhawvOZeceoLhmu424daK6cDBsBgkqhkiG9w0BCQ8xXzBdMAsGCWCGSAFlAwQBKjAL BglghkgBZQMEAQIwCgYIKoZIhvcNAwcwDgYIKoZIhvcNAwICAgCAMA0GCCqGSIb3DQMCAgFA MAcGBSsOAwIHMA0GCCqGSIb3DQMCAgEoMIGRBgkrBgEEAYI3EAQxgYMwgYAweTEQMA4GA1UE ChMHUm9vdCBDQTEeMBwGA1UECxMVaHR0cDovL3d3dy5jYWNlcnQub3JnMSIwIAYDVQQDExlD QSBDZXJ0IFNpZ25pbmcgQXV0aG9yaXR5MSEwHwYJKoZIhvcNAQkBFhJzdXBwb3J0QGNhY2Vy dC5vcmcCAxEt+DCBkwYLKoZIhvcNAQkQAgsxgYOggYAweTEQMA4GA1UEChMHUm9vdCBDQTEe MBwGA1UECxMVaHR0cDovL3d3dy5jYWNlcnQub3JnMSIwIAYDVQQDExlDQSBDZXJ0IFNpZ25p bmcgQXV0aG9yaXR5MSEwHwYJKoZIhvcNAQkBFhJzdXBwb3J0QGNhY2VydC5vcmcCAxEt+DAN BgkqhkiG9w0BAQEFAASCAgAYm3jH+qACbxCoQZyYx3UKJbxIjETAruQ+Fn/VGSBOBR87+tX5 0kBj8xLjk9U+zSFBeqtuUZq8ErYfHAWKdNuTJg9AB6mbSSKr7f5vwYWSALDxx94tcGKP/129 eSbHP8FKNxyoZPnAiG1fuqMVqAqYA0q+PeohYIJUDDDeZ8yDE9wYz2GeyUp0bvmLFhCkS+82 d5SUDQ7RVWI+sVf6E9ho0lb5R7s/3sCnYU+wwku/vQhUZUxQd528L4Ab4Sf52+KhRJlAuejJ Atmklald0ivu6itf/odS32HX6K1Pw1ZvjRq4ElTu491P+sVFyOz/7nVvESOu5m21OjGiGWuZ JvuCNhkKQFIF0zzogrJzyuRP2mIs7Obvf+IgSugabem/QWvDPgcLIu38Pbza0LoYif/D+mLN kVDYkf+S0zPCgHi45SwthOhrFBOi1ZczFq/nZQF/rSn/opzwi6IUt8ErDegGv6prUr7Vbxoy XL7/qEww35t5/mCahpIR0exWSIgYzgI3F8PnVsnx846eEnl1xdSahOrN28rt4ChiIeI4ZhR0 kOsbsT1CqwvvtFq68UKhc1CATM1XAu8UOelVuDt40tMktHwCui8cdsVNl9C8lGxJhLmgSjCX dXyDI0iKshuU3+dFbXk0ivAjwE3cOdN1KunlLIvV2yTflkqImR4QJZq9ugAAAAAAAA== --------------ms070409010700000709040405--