From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from plane.gmane.org ([80.91.229.3]:59011 "EHLO plane.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761234AbaGRKp6 (ORCPT ); Fri, 18 Jul 2014 06:45:58 -0400 Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1X85fl-0007CP-7M for linux-btrfs@vger.kernel.org; Fri, 18 Jul 2014 12:45:53 +0200 Received: from ip68-231-22-224.ph.ph.cox.net ([68.231.22.224]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Fri, 18 Jul 2014 12:45:53 +0200 Received: from 1i5t5.duncan by ip68-231-22-224.ph.ph.cox.net with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Fri, 18 Jul 2014 12:45:53 +0200 To: linux-btrfs@vger.kernel.org From: Duncan <1i5t5.duncan@cox.net> Subject: Re: Questions on incremental backups Date: Fri, 18 Jul 2014 10:45:37 +0000 (UTC) Message-ID: References: <1405627978.2630.39.camel@s-Air> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: Russell Coker posted on Fri, 18 Jul 2014 14:35:20 +1000 as excerpted: > Daily snapshots work welk with kernel 3.14 and above (I had problems > with 3.13 and previous). I have snapshots every 15 mins on some subvols. > > Very large numbers of snapshots can cause performance problems. I > suggest keeping below 1000 snapshots at this time. The other caveat with btrfs snapshots is how they deal with NOCOW files, the usual workaround recommended for large (Gig-ish-plus) internal- rewrite-pattern files such as databases and VM images. I'll avoid a detailed discussion here since I don't know whether it applies to the OP's use-case and the problem and workarounds are well discussed in other threads, but this is a heads-up for the OP to do a bit of research on the topic if he /does/ deal with gig-plus sized VM images or databases. Very briefly, putting such files on their own subvolume and using more traditional backup techniques instead of snapshotting is recommended. Another alternative is partitioning and choosing a filesystem other than btrfs for those files, while still considering btrfs for other files. -- Duncan - List replies preferred. No HTML msgs. "Every nonfree program has a lord, a master -- and if you use the program, he is your master." Richard Stallman