From mboxrd@z Thu Jan 1 00:00:00 1970 From: Theodore Ts'o Subject: Re: Question: errors=continue behaviour for failed external journal device Date: Sat, 26 Jul 2014 21:07:27 -0400 Message-ID: <20140727010727.GX6725@thunk.org> References: <20140727000733.GV6725@thunk.org> <53D44925.4000903@dobrotescu.ca> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-ext4@vger.kernel.org To: Vlad Dobrotescu Return-path: Received: from imap.thunk.org ([74.207.234.97]:58952 "EHLO imap.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751227AbaG0BH3 (ORCPT ); Sat, 26 Jul 2014 21:07:29 -0400 Content-Disposition: inline In-Reply-To: <53D44925.4000903@dobrotescu.ca> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Sat, Jul 26, 2014 at 08:34:45PM -0400, Vlad Dobrotescu wrote: > > Thanks for the quick and detailed answer. If I understand it correctly, > the errors= option has nothing to do with journaling, but only with FS > consistency issues (which can be caused by a vanished journal, The errors= option has to do with how the system will react when it discovered a file system inconsistency (for example, while deleting a file, it discovers that the blocks it is trying to free are already freed, etc.) errors=continue is the "don't worry, be happy" option --- and this can sometimes work out, it's much like ignoring a late mortgage payment notice from the bank. Most of the time, sooner or later, it catches up to you. :-) > by other events), while the mounting itself fails in the absence of the > device specified for external journaling, with no fall-back alternative. Your question about what happens if the journal is missing is much like the question, "suppose as I have a RAID 0 setup, and I'm missing one of the disks --- what can we do"? Basically, nothing. In a desperation scenario, there are ways you can forcibly tell the system to pretend that there is no journal, just like you can pretend that the system should ignore 20% of a missing RAID 0 array and have the LVM replace the missing disk with zero blocks --- but results are very likely to lead to data loss. Cheers, - Ted