From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.gocept.net ([195.62.125.19]:53473 "EHLO mail.gocept.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752607AbdC0Oxg (ORCPT ); Mon, 27 Mar 2017 10:53:36 -0400 From: Christian Theune Message-Id: <4E13254F-FDE8-47F7-A495-53BFED814C81@flyingcircus.io> Content-Type: multipart/signed; boundary="Apple-Mail=_90094307-A409-4E3E-B5B0-3F29978A053C"; protocol="application/pgp-signature"; micalg=pgp-sha512 Mime-Version: 1.0 (Mac OS X Mail 10.2 \(3259\)) Subject: Re: Shrinking a device - performance? Date: Mon, 27 Mar 2017 16:53:03 +0200 In-Reply-To: <20170327194847.5c0c5545@natsu> Cc: Hugo Mills , linux-btrfs@vger.kernel.org To: Roman Mamedov References: <1CCB3887-A88C-41C1-A8EA-514146828A42@flyingcircus.io> <20170327130730.GN11714@carfax.org.uk> <3558CE2F-0B8F-437B-966C-11C1392B81F2@flyingcircus.io> <20170327194847.5c0c5545@natsu> Sender: linux-btrfs-owner@vger.kernel.org List-ID: --Apple-Mail=_90094307-A409-4E3E-B5B0-3F29978A053C Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 Hi, > On Mar 27, 2017, at 4:48 PM, Roman Mamedov wrote: >=20 > On Mon, 27 Mar 2017 15:20:37 +0200 > Christian Theune wrote: >=20 >> (Background info: we=E2=80=99re 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=E2=80=99m all ears.) >=20 > 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. That is true. However, we do have moved the expected feature set of the = filesystem (i.e. cow) down to =E2=80=9Cstore files safely and = reliably=E2=80=9D and we=E2=80=99ve seen too much breakage with ext4 in = the past. Of course =E2=80=9Cpersistence means you=E2=80=99ll have to = say I=E2=80=99m sorry=E2=80=9D and thus with either choice we may be = faced with some issue in the future that we might have circumvented with = another solution and yes flexibility is worth a great deal. We=E2=80=99ve run XFS and ext4 on different (large and small) workloads = in the last 2 years and I have to say I=E2=80=99m much more happy about = XFS even with the shrinking limitation. To us ext4 is prohibitive with it=E2=80=99s fsck performance and we do = like the tight error checking in XFS. Thanks for the reminder though - especially in the public archive making = this tradeoff with flexibility known is wise to communicate. :-) Hugs, Christian -- Christian Theune =C2=B7 ct@flyingcircus.io =C2=B7 +49 345 219401 0 Flying Circus Internet Operations GmbH =C2=B7 http://flyingcircus.io Forsterstra=C3=9Fe 29 =C2=B7 06112 Halle (Saale) =C2=B7 Deutschland HR Stendal HRB 21169 =C2=B7 Gesch=C3=A4ftsf=C3=BChrer: Christian. = Theune, Christian. Zagrodnick --Apple-Mail=_90094307-A409-4E3E-B5B0-3F29978A053C Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=signature.asc Content-Type: application/pgp-signature; name=signature.asc Content-Description: Message signed with OpenPGP -----BEGIN PGP SIGNATURE----- Comment: GPGTools - https://gpgtools.org iQEcBAEBCgAGBQJY2SdPAAoJEKuh8lKpfGLOO+YH/RB1uRgZ+Lm+yMJevWSAJcgP FFbaXgYm/8qXP2K4VRjhHZtsFbe9hn61BoVzALXWZv8M2qVymjoAyGz+/JFBstFR 4V+ZSl6zkr8m2DcI/hsXm5UZ7UxckMaU/4eDeiPrndosXK3M06owmbJF7+UWfg1O GrhIBMDaayjl0RwkgMJPUiTqBQkqim42kPYYPLh7N2rMjLBeUW6yAk9JxGngASL8 7Zi3tcL7tnbfNkN5TRxSlFw6O2CXIijNUEj+kGJ4tJcSVTd+s/VkYQl/rB9U9ekV /N3L/mqshgufCSID6ddGUHwV5X5W86NAU/wxOZy9UG65HtOE1TouV5FJ9Rs+A5Q= =+Tsp -----END PGP SIGNATURE----- --Apple-Mail=_90094307-A409-4E3E-B5B0-3F29978A053C--