From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from len.romanrm.net ([195.154.117.182]:53632 "EHLO len.romanrm.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752146AbdC0OtQ (ORCPT ); Mon, 27 Mar 2017 10:49:16 -0400 Date: Mon, 27 Mar 2017 19:48:47 +0500 From: Roman Mamedov To: Christian Theune Cc: Hugo Mills , linux-btrfs@vger.kernel.org Subject: Re: Shrinking a device - performance? Message-ID: <20170327194847.5c0c5545@natsu> In-Reply-To: <3558CE2F-0B8F-437B-966C-11C1392B81F2@flyingcircus.io> References: <1CCB3887-A88C-41C1-A8EA-514146828A42@flyingcircus.io> <20170327130730.GN11714@carfax.org.uk> <3558CE2F-0B8F-437B-966C-11C1392B81F2@flyingcircus.io> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Mon, 27 Mar 2017 15:20:37 +0200 Christian Theune wrote: > (Background info: we’re migrating large volumes from btrfs to xfs and can > only do this step by step: copying some data, shrinking the btrfs volume, > extending the xfs volume, rinse repeat. If someone should have any > suggestions to speed this up and not having to think in terms of _months_ > then I’m all ears.) I would only suggest that you reconsider XFS. You can't shrink XFS, therefore you won't have the flexibility to migrate in the same way to anything better that comes along in the future (ZFS perhaps? or even Bcachefs?). XFS does not perform that much better over Ext4, and very importantly, Ext4 can be shrunk. >>From the looks of it Ext4 has also overcome its 16TB limitation: http://askubuntu.com/questions/779754/how-do-i-resize-an-ext4-partition-beyond-the-16tb-limit -- With respect, Roman