Date: Mon, 15 Jan 2018 18:28:10 -0600 (CST) From: Bob Friesenhahn <bfriesen@simple.dallas.tx.us> To: Mark Martinec <Mark.Martinec+freebsd@ijs.si> Cc: freebsd-fs@freebsd.org Subject: Re: Reducing ZFS fragmentation by copying to larger disk Message-ID: <alpine.GSO.2.20.1801151825420.18206@scrappy.simplesystems.org> In-Reply-To: <c2e1f7bd61bd080737e4b887e248d82a@ijs.si> References: <c2e1f7bd61bd080737e4b887e248d82a@ijs.si>
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On Tue, 16 Jan 2018, Mark Martinec wrote: > Having a ZFS filesystem with two 4 TB disks in a mirror that > is 85 % full and apparently pretty much fragmented (scrubs > or a resilver takes excessively long time), I intend to move > its contents to a new pair of disks twice the size. > > My question is what method to use so that in the end the copy will > be less fragmented: > > 1. attach new disks to a ZFS mirror and let them resilver, then > remove the old disks (Would the copied content be any less > fragmented, or perhaps would the added free space just > relieve some of the problem?) I don't think this would help with fragmentation at all. > 2. use zfs send / receive to make a copy > (is this any better than method #1 ?) This will work well as long as there is enough space to send to. It will even work within the same pool if there is enough free space. Bob -- Bob Friesenhahn bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/
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