Date: Tue, 09 Sep 2014 23:51:01 -0700 From: Peter Wemm <peter@wemm.org> To: freebsd-stable@freebsd.org Cc: Aristedes Maniatis <ari@ish.com.au> Subject: Re: getting to 4K disk blocks in ZFS Message-ID: <6384455.xLarv7m8fO@overcee.wemm.org> In-Reply-To: <540FF3C4.6010305@ish.com.au> References: <540FF3C4.6010305@ish.com.au>
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--nextPart1622072.FDWEii6vFl Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="us-ascii" On Wednesday, September 10, 2014 04:46:28 PM Aristedes Maniatis wrote: > As we all know, it is important to ensure that modern disks are set u= p > properly with the correct block size. Everything is good if all the d= isks > and the pool are "ashift=3D9" (512 byte blocks). But as soon as one n= ew drive > requires 4k blocks, performance drops through the floor of the enture= pool. [..] > And secondly, is it also bad to have ashift 9 disks inside a ashift 1= 2 pool? > That is, do we need to replace all our disks in one go and forever ke= ep big > sticky labels on each disk so we never mix them? For what its worth, in the freebsd.org cluster we automatically align=20= everything to a minimum of 4k, no matter what the actual drive is. We set: sysctl vfs.zfs.min_auto_ashift=3D12 (this saves a lot of messing around with gnop etc) and ensure all the gpt slices are 4k or better aligned. =2D-=20 Peter Wemm - peter@wemm.org; peter@FreeBSD.org; peter@yahoo-inc.com; KI= 6FJV UTF-8: for when a ' or ... just won\342\200\231t do\342\200\246 --nextPart1622072.FDWEii6vFl Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part. Content-Transfer-Encoding: 7Bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQEcBAABAgAGBQJUD/TaAAoJEDXWlwnsgJ4EQQMIAKq8KMWaXMqm1Wwhc4rfCl7x FgSiNZpvHu6fIhbwhEQCdsDwoq2igztanzemMh50Kz5TV9FBLs99ol20q1FKiKxv 385emfODj5uODDCiQTBnwjtk6yP/z2aOs7YWutFBgaM2Ar22oDEONgquwof+8hSj 4lIO8eOjb0yovI4EtOC0h79aOSSGsptRjAQGUQO4NeolLIyY5ZmVV+/mlKMQGL3c KW5VNWxOOC9ZV9rtwtjLn2TeZfS5a6kaeYzr3fB6SGhDQStQrMyWLisp+g/Tqafa SUoIxFInZL8tZ/d+YlELsd/aRniHcfKsiGYDESrzeXT3Bgwv4vw75PTFd89t58A= =WOXD -----END PGP SIGNATURE----- --nextPart1622072.FDWEii6vFl--
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