From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ie0-f169.google.com ([209.85.223.169]:48359 "EHLO mail-ie0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751438AbaFPLKk (ORCPT ); Mon, 16 Jun 2014 07:10:40 -0400 Received: by mail-ie0-f169.google.com with SMTP id at1so4860972iec.14 for ; Mon, 16 Jun 2014 04:10:40 -0700 (PDT) Message-ID: <539ED083.5050705@gmail.com> Date: Mon, 16 Jun 2014 07:09:55 -0400 From: Austin S Hemmelgarn MIME-Version: 1.0 To: =?ISO-8859-1?Q?Sw=E2mi_Petaramesh?= , Linux BTRFS Subject: Re: BTRFS, SSD and single metadata References: <1723493.aXdklhDgAK@vajra> In-Reply-To: <1723493.aXdklhDgAK@vajra> Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha1; boundary="------------ms030902030906000600060706" Sender: linux-btrfs-owner@vger.kernel.org List-ID: This is a cryptographically signed message in MIME format. --------------ms030902030906000600060706 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On 2014-06-16 03:54, Sw=E2mi Petaramesh wrote: > Hi, >=20 > I created a BTRFS filesytem over LVM over LUKS encryption on an SSD [ye= s, I=20 > know...], and I noticed that the FS got created with metadata in "DUP" = mode,=20 > contrary to what "man mkfs.btrfs" says for SSDs -> it would be supposed= to be=20 > "SINGLE"... >=20 > Well I don't know if my system didn't identify the SSD because of the L= VM+LUKS=20 > stack (however it mounts well by itself with the "ssd" flag and accepts= the=20 > "discard" option [yes, I know...]), or if the manpage is obsolete or if= this=20 > feature just doesn't work...? >=20 > The SSD being a Micron RealSSD C400 >=20 > For both SSD preservation and data integrity, would it be advisable to = change=20 > metadata to "SINGLE" using a rebalance, or if I'd better just leave thi= ngs the=20 > way they are...? >=20 > TIA for any insight. >=20 What mkfs.btrfs looks at is /sys/block//queue/rotational, if that is 1 it knows that the device isn't a SSD. I believe that LVM passes through whatever the next lower layer's value is, but dmcrypt (and by extension LUKS) always force it to a 1 (possibly to prevent programs from using heuristics for enabling discard) --------------ms030902030906000600060706 Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="smime.p7s" Content-Description: S/MIME Cryptographic Signature MIAGCSqGSIb3DQEHAqCAMIACAQExCzAJBgUrDgMCGgUAMIAGCSqGSIb3DQEHAQAAoIIGuDCC BrQwggScoAMCAQICAw8BRDANBgkqhkiG9w0BAQ0FADB5MRAwDgYDVQQKEwdSb290IENBMR4w HAYDVQQLExVodHRwOi8vd3d3LmNhY2VydC5vcmcxIjAgBgNVBAMTGUNBIENlcnQgU2lnbmlu ZyBBdXRob3JpdHkxITAfBgkqhkiG9w0BCQEWEnN1cHBvcnRAY2FjZXJ0Lm9yZzAeFw0xNDA1 MTIxNDEwMzJaFw0xNDExMDgxNDEwMzJaMGMxGDAWBgNVBAMTD0NBY2VydCBXb1QgVXNlcjEj MCEGCSqGSIb3DQEJARYUYWhmZXJyb2luN0BnbWFpbC5jb20xIjAgBgkqhkiG9w0BCQEWE2Fo ZW1tZWxnQG9oaW9ndC5jb20wggIiMA0GCSqGSIb3DQEBAQUAA4ICDwAwggIKAoICAQDbLUaL Gs4JTdU7sgr0MzD57CMUAv307ddC9pxooDMN3PiUvzEd5kLtBCh8KDB1wbMdfm4hte2rDd+j hM1tIq67BvNbdDPztOcBZwT2/3OVyyG4B1ddCqUyt03zGKw6Y34eHNfapsZiiItX0GBNfjHU Wv+WDo+XNha/WmGSSMv21HkftF9XA1KC9Bpr9JJI23MKK7T2g/7b3KoGZlx3ekLIJsF5B7+B DMPPDqOHQbRnccyOHEMyhM13g6WoAbU+3aKYc+C/9UsYtDV+xlvBLWagky1acstD5wOA35V6 uDRbUhD+vOjuMRMCj9jJOIYqa6AeSagBjxRnisJr0RFzQ4f+NjGCHPaFTvRvbkiXh4q22doT 0SxbNBUm7B9ANugIOtS9/VQhTWKDi//WTqZQ7Ecl4yVJbMCUg/iaRHMCGS41vqMICPszRidW rL04NwS9D2cREEY1y/xrNo0ZvKPZu6tLhxhPf7w+5rsN3+wWxGaR1hNpnVUT9AeacLKZO6W9 FsRT3Unkr91IhQATHTKYr4EAkjN/5lgvA+sxp5TxxsUnoJYrD8IHf8aYfJsAHMleBwx4xSeZ tw/n5iIjJjFZq9IRZ1zQhK62p+a5vJ2vlJHjTgavhQrfb1pUOjbqsnI4ndQ5hNosL9el4Kxq Yko+HsxVEmSwSsjq6cV2L3oz0z8NUwIDAQABo4IBWTCCAVUwDAYDVR0TAQH/BAIwADBWBglg hkgBhvhCAQ0ESRZHVG8gZ2V0IHlvdXIgb3duIGNlcnRpZmljYXRlIGZvciBGUkVFIGhlYWQg b3ZlciB0byBodHRwOi8vd3d3LkNBY2VydC5vcmcwDgYDVR0PAQH/BAQDAgOoMEAGA1UdJQQ5 MDcGCCsGAQUFBwMEBggrBgEFBQcDAgYKKwYBBAGCNwoDBAYKKwYBBAGCNwoDAwYJYIZIAYb4 QgQBMDIGCCsGAQUFBwEBBCYwJDAiBggrBgEFBQcwAYYWaHR0cDovL29jc3AuY2FjZXJ0Lm9y ZzAxBgNVHR8EKjAoMCagJKAihiBodHRwOi8vY3JsLmNhY2VydC5vcmcvcmV2b2tlLmNybDA0 BgNVHREELTArgRRhaGZlcnJvaW43QGdtYWlsLmNvbYETYWhlbW1lbGdAb2hpb2d0LmNvbTAN BgkqhkiG9w0BAQ0FAAOCAgEAIokFPcW8+cO2Clu0Ei+ehAmQRBHfV5RWJ8aMVLXOCfiJX0ch IjVSIt6I3uQaR4J1ZIAjCSPkbpfZQDaLoGFI5j8aYEQhOeKxrvOMzY9/aSUYabCJIhE/sX64 klFV0bzm+PR9cDMWeQ9BoZf0m8UROPSfDnrjEk+p04hGg3pAZMcSwCzxdb604NHjgHJmf2xG UQVzQgC6Ek/BKat0xuPTuPmtPv9OicK75CPmLZKYW3rFpCD6bhb1mm+ROcCNhniRY2LYm9YN QdlHQUzTFqj0tvuYrzNI3LNV4PjEfN8z6omPCT2Rq8/uKLseN+m8F0ioqm+cphqpmzKoDUpN nePLkqDFUFWCeWRxSjBTy4IMVUfdNXriVGihH8hyIICQiOfmmBOzhzUifdomJuTGtoXRuHVT R2f/YdrJrLnKI4f+Othdp7F3KhB4c6JiOnTEH5J8n9q3rFjt4MPRwcjIHMhmF5nZVQlgxEMo 1cPCmvG1D9tcgXbH79jjqydo9SDXhzLQob7axkzGRY96IstNcvoQ/UNsdPPfFMYlHtGz4TxT DhBjv4ERskGmKBZrfmxkXkcuTV/gcykct6Xvw9YXb8WTL4qSYHSYk9fReVLgE/L4RBUpX2JJ QvIR0AJLER165/aZlQXZtuJjnfxJtJTJZZ+Gor9h0G2kuR5Dy0JuYdBO4t4xggShMIIEnQIB ATCBgDB5MRAwDgYDVQQKEwdSb290IENBMR4wHAYDVQQLExVodHRwOi8vd3d3LmNhY2VydC5v cmcxIjAgBgNVBAMTGUNBIENlcnQgU2lnbmluZyBBdXRob3JpdHkxITAfBgkqhkiG9w0BCQEW EnN1cHBvcnRAY2FjZXJ0Lm9yZwIDDwFEMAkGBSsOAwIaBQCgggH1MBgGCSqGSIb3DQEJAzEL BgkqhkiG9w0BBwEwHAYJKoZIhvcNAQkFMQ8XDTE0MDYxNjExMDk1NVowIwYJKoZIhvcNAQkE MRYEFDUmvUxzaPsVhwz2ih7uYPDe0NisMGwGCSqGSIb3DQEJDzFfMF0wCwYJYIZIAWUDBAEq MAsGCWCGSAFlAwQBAjAKBggqhkiG9w0DBzAOBggqhkiG9w0DAgICAIAwDQYIKoZIhvcNAwIC AUAwBwYFKw4DAgcwDQYIKoZIhvcNAwICASgwgZEGCSsGAQQBgjcQBDGBgzCBgDB5MRAwDgYD VQQKEwdSb290IENBMR4wHAYDVQQLExVodHRwOi8vd3d3LmNhY2VydC5vcmcxIjAgBgNVBAMT GUNBIENlcnQgU2lnbmluZyBBdXRob3JpdHkxITAfBgkqhkiG9w0BCQEWEnN1cHBvcnRAY2Fj ZXJ0Lm9yZwIDDwFEMIGTBgsqhkiG9w0BCRACCzGBg6CBgDB5MRAwDgYDVQQKEwdSb290IENB MR4wHAYDVQQLExVodHRwOi8vd3d3LmNhY2VydC5vcmcxIjAgBgNVBAMTGUNBIENlcnQgU2ln bmluZyBBdXRob3JpdHkxITAfBgkqhkiG9w0BCQEWEnN1cHBvcnRAY2FjZXJ0Lm9yZwIDDwFE MA0GCSqGSIb3DQEBAQUABIICAGuYkSaLth4EwMLxkfdeKSqcf3U57XXPBzlQA8KYqmZEybJM SURNoovxgEqYzdrbFN+ULLfCNQGk1gpoyvQN5S/ibU4eluIROOnSiXKUrk0Rx67Ew6lGmwKA eNNYIhzRhQ69V9tyOnNXxPEOUqiJcBKU/vj6Sh0cHTg1pnXuOjrPBdEVSyL+gGf9c9iH/s76 3LF9XU9eShaETn5gJr7FtMLzq79VGFGXxm6Y/BQ/FII/lo7QwPFF2CoqmEh4XQIT3/kcuWG4 CeusVdJUMx9uxDoPAvLsLSmX6J5aQ8vwEDfV1Bv3zi7l9CxNfR9z1VjPV+sG6Og9H0uxq9x1 k56KtD0tglLR2bVcd4uDP/3RjuGCnhfySHtsuObvqee6g8OSgBLFeqIA7d57JRMYrGbLTHVt dZAsWcClu9h+Bbd/5yrBJ5DeBtge7bktMMDyBOa0tu1RlgoBvng7RcxXgcKehcorfso6Xivn WPIp4rUfO5cORLbQen07jXZDYgopeAqKhyqUfC8/0y8mH2VN9KTFsKzM/pFCbIbD6Al0pi1W ykqmKBfhYx/py6wv9kcQdPyNc4cs5RzOZpPzZ4Yk5syfTK3qTL9p+IXBEzecP3BqXwByPgzQ rjs241FcFUkGPTmi2AFLfiOSTBk20dWq55tWQaqv/JsALUNEgsqOMqobdDQJAAAAAAAA --------------ms030902030906000600060706--