From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ig0-f180.google.com ([209.85.213.180]:62787 "EHLO mail-ig0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751703AbaJJTfl (ORCPT ); Fri, 10 Oct 2014 15:35:41 -0400 Received: by mail-ig0-f180.google.com with SMTP id uq10so4003664igb.13 for ; Fri, 10 Oct 2014 12:35:41 -0700 (PDT) Message-ID: <543834FC.9050409@gmail.com> Date: Fri, 10 Oct 2014 15:35:24 -0400 From: Austin S Hemmelgarn MIME-Version: 1.0 To: Bob Marley , linux-btrfs Subject: Re: What is the vision for btrfs fs repair? References: <54358C77.2070808@redhat.com> <9251D9EB-5B12-4885-8C6B-FFA10B1CDA24@colorremedies.com> <5437BAB2.1040605@shiftmail.org> <93B9D2BD-1F0F-4C94-899F-16A3A2A0D57E@colorremedies.com> <54381ADB.2030002@shiftmail.org> In-Reply-To: <54381ADB.2030002@shiftmail.org> Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha1; boundary="------------ms090202010902060707020606" Sender: linux-btrfs-owner@vger.kernel.org List-ID: This is a cryptographically signed message in MIME format. --------------ms090202010902060707020606 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable On 2014-10-10 13:43, Bob Marley wrote: > On 10/10/2014 16:37, Chris Murphy wrote: >> The fail safe behavior is to treat the known good tree root as the >> default tree root, and bypass the bad tree root if it cannot be >> repaired, so that the volume can be mounted with default mount options= >> (i.e. the ones in fstab). Otherwise it's a filesystem that isn't well >> suited for general purpose use as rootfs let alone for boot. >> > > A filesystem which is suited for "general purpose" use is a filesystem > which honors fsync, and doesn't *ever* auto-roll-back without user > intervention. > > Anything different is not suited for database transactions at all. Any > paid service which has the users database on btrfs is going to be at > risk of losing payments, and probably without the company even knowing.= > If btrfs goes this way I hope a big warning is written on the wiki and > on the manpages telling that this filesystem is totally unsuitable for > hosting databases performing transactions. If they need reliability, they should have some form of redundancy=20 in-place and/or run the database directly on the block device; because=20 even ext4, XFS, and pretty much every other filesystem can lose data=20 sometimes, the difference being that those tend to give worse results=20 when hardware is misbehaving than BTRFS does, because BTRFS usually has=20 a old copy of whatever data structure gets corrupted to fall back on. Also, you really shouldn't be running databases on a BTRFS filesystem at = the moment anyway, because of the significant performance implications. > > At most I can suggest that a flag in the metadata be added to > allow/disallow auto-roll-back-on-error on such filesystem, so people ca= n > decide the "tolerant" vs. "transaction-safe" mode at filesystem creatio= n. > The problem with this is that if the auto-recovery code did run (and=20 IMHO the kernel should spit out a warning to the system log whenever it=20 does), then chances are that you wouldn't have had a consistent view if=20 you had prevented it from running either; and, if the database is=20 properly distributed/replicated, then it should recover by itself. --------------ms090202010902060707020606 Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="smime.p7s" Content-Description: S/MIME Cryptographic Signature MIAGCSqGSIb3DQEHAqCAMIACAQExCzAJBgUrDgMCGgUAMIAGCSqGSIb3DQEHAQAAoIIFuDCC BbQwggOcoAMCAQICAw9gVDANBgkqhkiG9w0BAQ0FADB5MRAwDgYDVQQKEwdSb290IENBMR4w HAYDVQQLExVodHRwOi8vd3d3LmNhY2VydC5vcmcxIjAgBgNVBAMTGUNBIENlcnQgU2lnbmlu ZyBBdXRob3JpdHkxITAfBgkqhkiG9w0BCQEWEnN1cHBvcnRAY2FjZXJ0Lm9yZzAeFw0xNDA4 MDgxMTMwNDRaFw0xNTAyMDQxMTMwNDRaMGMxGDAWBgNVBAMTD0NBY2VydCBXb1QgVXNlcjEj MCEGCSqGSIb3DQEJARYUYWhmZXJyb2luN0BnbWFpbC5jb20xIjAgBgkqhkiG9w0BCQEWE2Fo ZW1tZWxnQG9oaW9ndC5jb20wggEiMA0GCSqGSIb3DQEBAQUAA4IBDwAwggEKAoIBAQDdmm8R BM5D6fGiB6rpogPZbLYu6CkU6834rcJepfmxKnLarYUYM593/VGygfaaHAyuc8qLaRA3u1M0 Qp29flqmhv1VDTBZ+zFu6JgHjTDniBii1KOZRo0qV3jC5NvaS8KUM67+eQBjm29LhBWVi3+e a8jLxmogFXV0NGej+GHIr5zA9qKz2WJOEoGh0EfqZ2MQTmozcGI43/oqIYhRj8fRMkWXLUAF WsLzPQMpK19hD8fqwlxQWhBV8gsGRG54K5pyaQsjne7m89SF5M8JkNJPH39tHEvfv2Vhf7EM Y4WGyhLAULSlym1AI1uUHR1FfJaj3AChaEJZli/AdajYsqc7AgMBAAGjggFZMIIBVTAMBgNV HRMBAf8EAjAAMFYGCWCGSAGG+EIBDQRJFkdUbyBnZXQgeW91ciBvd24gY2VydGlmaWNhdGUg Zm9yIEZSRUUgaGVhZCBvdmVyIHRvIGh0dHA6Ly93d3cuQ0FjZXJ0Lm9yZzAOBgNVHQ8BAf8E BAMCA6gwQAYDVR0lBDkwNwYIKwYBBQUHAwQGCCsGAQUFBwMCBgorBgEEAYI3CgMEBgorBgEE AYI3CgMDBglghkgBhvhCBAEwMgYIKwYBBQUHAQEEJjAkMCIGCCsGAQUFBzABhhZodHRwOi8v b2NzcC5jYWNlcnQub3JnMDEGA1UdHwQqMCgwJqAkoCKGIGh0dHA6Ly9jcmwuY2FjZXJ0Lm9y Zy9yZXZva2UuY3JsMDQGA1UdEQQtMCuBFGFoZmVycm9pbjdAZ21haWwuY29tgRNhaGVtbWVs Z0BvaGlvZ3QuY29tMA0GCSqGSIb3DQEBDQUAA4ICAQCr4klxcZU/PDRBpUtlb+d6JXl2dfto OUP/6g19dpx6Ekt2pV1eujpIj5whh5KlCSPUgtHZI7BcksLSczQbxNDvRu6LNKqGJGvcp99k cWL1Z6BsgtvxWKkOmy1vB+2aPfDiQQiMCCLAqXwHiNDZhSkwmGsJ7KHMWgF/dRVDnsl6aOQZ jAcBMpUZxzA/bv4nY2PylVdqJWp9N7x86TF9sda1zRZiyUwy83eFTDNzefYPtc4MLppcaD4g Wt8U6T2ffQfCWVzDirhg4WmDH3MybDItjkSB2/+pgGOS4lgtEBMHzAGQqQ+5PojTHRyqu9Jc O59oIGrTaOtKV9nDeDtzNaQZgygJItJi9GoAl68AmIHxpS1rZUNV6X8ydFrEweFdRTVWhUEL 70Cnx84YBojXv01LYBSZaq18K8cERPLaIrUD2go+2ffjdE9ejvYDhNBllY+ufvRizIjQA1uC OdktVAN6auQob94kOOsWpoMSrzHHvOvVW/kbokmKzaLtcs9+nJoL+vPi2AyzbaoQASVZYOGW pE3daA0F5FJfcPZKCwd5wdnmT3dU1IRUxa5vMmgjP20lkfP8tCPtvZv2mmI2Nw5SaXNY4gVu WQrvkV2in+TnGqgEIwUrLVbx9G6PSYZZs07czhO+Q1iVuKdAwjL/AYK0Us9v50acIzbl5CWw ZGj3wjGCA6EwggOdAgEBMIGAMHkxEDAOBgNVBAoTB1Jvb3QgQ0ExHjAcBgNVBAsTFWh0dHA6 Ly93d3cuY2FjZXJ0Lm9yZzEiMCAGA1UEAxMZQ0EgQ2VydCBTaWduaW5nIEF1dGhvcml0eTEh MB8GCSqGSIb3DQEJARYSc3VwcG9ydEBjYWNlcnQub3JnAgMPYFQwCQYFKw4DAhoFAKCCAfUw GAYJKoZIhvcNAQkDMQsGCSqGSIb3DQEHATAcBgkqhkiG9w0BCQUxDxcNMTQxMDEwMTkzNTI0 WjAjBgkqhkiG9w0BCQQxFgQUfGdGHQhprgVwMYaJqG9dt5B/zXEwbAYJKoZIhvcNAQkPMV8w XTALBglghkgBZQMEASowCwYJYIZIAWUDBAECMAoGCCqGSIb3DQMHMA4GCCqGSIb3DQMCAgIA gDANBggqhkiG9w0DAgIBQDAHBgUrDgMCBzANBggqhkiG9w0DAgIBKDCBkQYJKwYBBAGCNxAE MYGDMIGAMHkxEDAOBgNVBAoTB1Jvb3QgQ0ExHjAcBgNVBAsTFWh0dHA6Ly93d3cuY2FjZXJ0 Lm9yZzEiMCAGA1UEAxMZQ0EgQ2VydCBTaWduaW5nIEF1dGhvcml0eTEhMB8GCSqGSIb3DQEJ ARYSc3VwcG9ydEBjYWNlcnQub3JnAgMPYFQwgZMGCyqGSIb3DQEJEAILMYGDoIGAMHkxEDAO BgNVBAoTB1Jvb3QgQ0ExHjAcBgNVBAsTFWh0dHA6Ly93d3cuY2FjZXJ0Lm9yZzEiMCAGA1UE AxMZQ0EgQ2VydCBTaWduaW5nIEF1dGhvcml0eTEhMB8GCSqGSIb3DQEJARYSc3VwcG9ydEBj YWNlcnQub3JnAgMPYFQwDQYJKoZIhvcNAQEBBQAEggEAAJ5i0P2AurdB68PM+3FmK2ezE2DA njBNEea6UYrqCp5xm4m0KOY+f3eiVajcd+9ikTEzrKe1hcOU4gLObHkAy0IXwNdXoxafwP7l R4FGHRpPh8eS0ivRBOCqY6Tzai9KMIugAVkTh4Gf7XcohhGMLd73xbH0Slc+OiSObJjOt4oA HDXE5u3xCrde36O6yRRaf3cVPpUqtmfAfBptVaM5/zt6gNlcolrbN1nx7W4VGehpx5ZKL7x/ bsHkaH6HzZZOd7FXFQtD8L7gs+CAdwxlvkIMfUbC/cAnHBiYDwhVHDLsl0epuTUgwT/B8/kv vAxl6Xdv+YHjlzE8gbICRrw81gAAAAAAAA== --------------ms090202010902060707020606--