From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ig0-f172.google.com ([209.85.213.172]:34317 "EHLO mail-ig0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2993454AbbEEPot (ORCPT ); Tue, 5 May 2015 11:44:49 -0400 Received: by iget9 with SMTP id t9so80942066ige.1 for ; Tue, 05 May 2015 08:44:48 -0700 (PDT) Message-ID: <5548E56A.3040407@gmail.com> Date: Tue, 05 May 2015 11:44:42 -0400 From: Austin S Hemmelgarn MIME-Version: 1.0 To: Rory Jaffe , linux-btrfs@vger.kernel.org Subject: Re: fstab: use UUID or labe? References: In-Reply-To: Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha1; boundary="------------ms000606080005060801090103" Sender: linux-btrfs-owner@vger.kernel.org List-ID: This is a cryptographically signed message in MIME format. --------------ms000606080005060801090103 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable On 2015-05-04 21:42, Rory Jaffe wrote: > Question about fault tolerance and choice of ID. I'm running btrfs > with subvolumes for / and /home. /boot and grub are on a thumb drive. > I have six drives in the system, running raid1 for both data and > metadata. > > When I run "sudo btrfs fi show" it provides both the label and the > uuid. The UUID shown is the same as that for the first partition that > btrfs was installed on. > > In fstab, the mount points currently use that UUID to identify the file= system. > > If the original drive fails, will that UUID still point to the > filesystem, or is it better to use the label for the filesystem? Will > the filesystem mount in either case with the failure of the original > drive? > The UUID itself refers to the filesystem as a whole, not that specific=20 partition, so even if the original drive fails, the UUID will still=20 properly reference the filesystem (whether or not you can mount it is a=20 whole separate issue, as a missing device usually means you need some=20 manual intervention for recovery). Personally, I prefer to use labels in fstab, as it makes it much more=20 obvious what is what ( and labels are usually much more compact than=20 UUID's), although this can cause issues if you aren't careful (multiple=20 filesystems with the same label gets really interesting when trying to=20 mount by label). Additionally, on sufficiently recent distributions,=20 you might be able to use PARTUUID or PARTLABEL to id individual=20 partitions in /etc/fstab, although the disk needs to have a partition=20 table format that actually supports this (GPT is the only one I know of, = although there may be others). --------------ms000606080005060801090103 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 BrQwggScoAMCAQICAxBuVTANBgkqhkiG9w0BAQ0FADB5MRAwDgYDVQQKEwdSb290IENBMR4w HAYDVQQLExVodHRwOi8vd3d3LmNhY2VydC5vcmcxIjAgBgNVBAMTGUNBIENlcnQgU2lnbmlu ZyBBdXRob3JpdHkxITAfBgkqhkiG9w0BCQEWEnN1cHBvcnRAY2FjZXJ0Lm9yZzAeFw0xNTAz MjUxOTM0MzhaFw0xNTA5MjExOTM0MzhaMGMxGDAWBgNVBAMTD0NBY2VydCBXb1QgVXNlcjEj MCEGCSqGSIb3DQEJARYUYWhmZXJyb2luN0BnbWFpbC5jb20xIjAgBgkqhkiG9w0BCQEWE2Fo ZW1tZWxnQG9oaW9ndC5jb20wggIiMA0GCSqGSIb3DQEBAQUAA4ICDwAwggIKAoICAQCdD/zW 2rRAFCLnDfXpWxU1+ODqRVUgzHvrRO7ADUxRo1CBDc3JSX5TIW2OGmQ3DAKGOACp8Z0sgxMc B05tzAZ/M7m4jajVrwwdVCdrwVGxTdAai7Kwg4ZCVfyMVhcwo8R2eW3QahBx34G0RKumK9sZ ZQSQ+zULAzpY6uz7T1sAk/erMoivRXF6u8WvOsLkOD1F/Xyv1ZccSUG5YeDgZgc0nZUBvyIp zXSHjgWerFkrxEM3y2z/Ff3eL1sgGYecV/I1F+I5S01V7Kclt/qRW10c/4JEGRcI1FmrJBPu BtMYPbg/3Y9LZROYN+mVIFxZxOfrmjfFZ96xt/TaMXo8vcEKtWcNEjhGBjEbfMUEm4aq8ygQ 4MuEcpJc8DJCHBkg2KBk13DkbU2qNepTD6Uip1C+g+KMr0nd6KOJqSH27ZuNY4xqV4hIxFHp ex0zY7mq6fV2o6sKBGQzRdI20FDYmNjsLJwjH6qJ8laxFphZnPRpBThmu0AjuBWE72GnI1oA aO+bs92MQGJernt7hByCnDO82W/ykbVz+Ge3Sax8NY0m2Xdvp6WFDY/PjD9CdaJ9nwQGsUSa N54lrZ2qMTeCI9Vauwf6U69BA42xgk65VvxvTNqji+tZ4aZbarZ7el2/QDHOb/rRwlCFplS/ z4l1f1nOrE6bnDl5RBJyW3zi74P6GwIDAQABo4IBWTCCAVUwDAYDVR0TAQH/BAIwADBWBglg hkgBhvhCAQ0ESRZHVG8gZ2V0IHlvdXIgb3duIGNlcnRpZmljYXRlIGZvciBGUkVFIGhlYWQg b3ZlciB0byBodHRwOi8vd3d3LkNBY2VydC5vcmcwDgYDVR0PAQH/BAQDAgOoMEAGA1UdJQQ5 MDcGCCsGAQUFBwMEBggrBgEFBQcDAgYKKwYBBAGCNwoDBAYKKwYBBAGCNwoDAwYJYIZIAYb4 QgQBMDIGCCsGAQUFBwEBBCYwJDAiBggrBgEFBQcwAYYWaHR0cDovL29jc3AuY2FjZXJ0Lm9y ZzAxBgNVHR8EKjAoMCagJKAihiBodHRwOi8vY3JsLmNhY2VydC5vcmcvcmV2b2tlLmNybDA0 BgNVHREELTArgRRhaGZlcnJvaW43QGdtYWlsLmNvbYETYWhlbW1lbGdAb2hpb2d0LmNvbTAN BgkqhkiG9w0BAQ0FAAOCAgEAGvl7xb42JMRH5D/vCIDYvFY3dR2FPd5kmOqpKU/fvQ8ovmJa p5N/FDrsCL+YdslxPY+AAn78PYmL5pFHTdRadT++07DPIMtQyy2qd+XRmz6zP8Il7vGcEDmO WmMLYMq4xV9s/N7t7JJp6ftdIYUcoTVChUgilDaRWMLidtslCdRsBVfUjPb1bF5Ua31diKDP e0M9/e2CU36rbcTtiNCXhptMigzuL3zJXUf2B9jyUV8pnqNEQH36fqJ7YTBLcpq3aYa2XbAH Hgx9GehJBIqwspDmhPCFZ/QmqUXCkt+XfvinQ2NzKR6P3+OdYbwqzVX8BdMeojh7Ig8x/nIx mQ+/ufstL1ZYp0bg13fyK/hPYSIBpayaC76vzWovkIm70DIDRIFLi20p/qTd7rfDYy831Hjm +lDdCECF9bIXEWFk33kA97dgQIMbf5chEmlFg8S0e4iw7LMjvRqMX3eCD8GJ2+oqyZUwzZxy S0Mx+rBld5rrN7LsXwZ671HsGqNeYbYeU25e7t7/Gcc6Bd/kPfA+adEuUGFcvUKH3trDYqNq 6mOkAd8WO/mQadlc3ztS++XDMhmIpfBre9MPAr6usqf+wc+R8Nk9KLK39kEgrqVfzc/fgf8L MaD4rHnusdg4gca6Yi+kNrm99anw7SwaBrBvULYBp7ixNRUhaYiNW4YjTrYxggShMIIEnQIB ATCBgDB5MRAwDgYDVQQKEwdSb290IENBMR4wHAYDVQQLExVodHRwOi8vd3d3LmNhY2VydC5v cmcxIjAgBgNVBAMTGUNBIENlcnQgU2lnbmluZyBBdXRob3JpdHkxITAfBgkqhkiG9w0BCQEW EnN1cHBvcnRAY2FjZXJ0Lm9yZwIDEG5VMAkGBSsOAwIaBQCgggH1MBgGCSqGSIb3DQEJAzEL BgkqhkiG9w0BBwEwHAYJKoZIhvcNAQkFMQ8XDTE1MDUwNTE1NDQ0MlowIwYJKoZIhvcNAQkE MRYEFGweXVWvNvBYlFigpn6QV6qt5rN7MGwGCSqGSIb3DQEJDzFfMF0wCwYJYIZIAWUDBAEq MAsGCWCGSAFlAwQBAjAKBggqhkiG9w0DBzAOBggqhkiG9w0DAgICAIAwDQYIKoZIhvcNAwIC AUAwBwYFKw4DAgcwDQYIKoZIhvcNAwICASgwgZEGCSsGAQQBgjcQBDGBgzCBgDB5MRAwDgYD VQQKEwdSb290IENBMR4wHAYDVQQLExVodHRwOi8vd3d3LmNhY2VydC5vcmcxIjAgBgNVBAMT GUNBIENlcnQgU2lnbmluZyBBdXRob3JpdHkxITAfBgkqhkiG9w0BCQEWEnN1cHBvcnRAY2Fj ZXJ0Lm9yZwIDEG5VMIGTBgsqhkiG9w0BCRACCzGBg6CBgDB5MRAwDgYDVQQKEwdSb290IENB MR4wHAYDVQQLExVodHRwOi8vd3d3LmNhY2VydC5vcmcxIjAgBgNVBAMTGUNBIENlcnQgU2ln bmluZyBBdXRob3JpdHkxITAfBgkqhkiG9w0BCQEWEnN1cHBvcnRAY2FjZXJ0Lm9yZwIDEG5V MA0GCSqGSIb3DQEBAQUABIICAGvRWDJSfDfyr37dNRKK/F9HDXAAWCMQEqPgrk6i8pqGoEhR +R7dMDD9GLHlfc57b9IplAz/D/dvA4YG5CsTzqhljNugMSG+a/WIQZeDwlfvHd8QufQrlY/b EKWslSlEAo1hwHYnDjUNMC4CBRsunvPgZ9yOd5tnxeT0BTk3kco/HZFcFqonXkAKhr/Yl4Yw vQjE8rjtkq10bSE7hDaDSNomPemWKvr/nY6iRZkqmGXavBZ+kWEKgJV3TwpPQYquicznM5TH CmJJON/6V11Je+jvpCFxHgw3zqPEJNMHWqm6Wy4ESFNrbQ1/d8GyfOh7oBfRR+JMbG0AjFO9 hmDZuFNclj6iGaO90WNLkl3EmF1/LBPxyxUFLksTnCBznSTW9q5P+yp3i5/Kx2YrGhHAWDtY 6ulvoB464JvrSPiouLgsd1YXyzE9C+YaiLdAAgH9JrVGZCjG+9b+VLwxy5EjOSN2xNGoiI/3 BIFOvCaCHi9MK0clRacrSFMnl2DPKDOxz4TN4IeNMbju98O1cOreEA7zKl6aoj9wj6me4pIq 82ElTCRqTCk5rbPm3bfXnzcBtZ+Pj+D2bmAE202xupdPdFU97gw1hrjkPzpPsLkKNrXk8Vb4 NRtp6PkmP764o73JK4dVw3QET59L9IOlDMfYE5wEIr12l/NEwUqAwetUJ80AAAAAAAAA --------------ms000606080005060801090103--