Date: Thu, 16 May 2019 00:29:16 +0200 From: Miroslav Lachman <000.fbsd@quip.cz> To: Peter <pmc@citylink.dinoex.sub.org>, freebsd-fs@freebsd.org Subject: Re: Waht is the minimum free space between GPT partitions? Message-ID: <60d57363-eb5c-e985-82ad-30f03b06a4c6@quip.cz> In-Reply-To: <20190515204243.GA67445@gate.oper.dinoex.org> References: <20190515204243.GA67445@gate.oper.dinoex.org>
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Peter wrote on 2019/05/15 22:42: > It appears I can't find an answeer anywhere: > > What is the recommendend safety distance (free space) between two > GPT partitions? > > I found, if I put partitions directly together (so that another starts > immediately after one ends), under certain circumstances the volumes > become inaccessible and the system (11.2) does crash. Obviousely there > is a safety distance required - but how big should it be? I read your post on forum https://forums.freebsd.org/threads/create-degraded-raid-5-with-2-disks-on-freebsd.70750/#post-426756 There is no requirement to have empty space between partitions. These 2 disks 6T each are partitioned with GPT and each partition is mirrored by gmirror: ~/> gpart show => 34 11721045101 ada0 GPT (5.5T) 34 6 - free - (3.0K) 40 1024 1 freebsd-boot (512K) 1064 984 - free - (492K) 2048 2097152 2 freebsd-ufs (1.0G) 2099200 16777216 3 freebsd-swap (8.0G) 18876416 16777216 4 freebsd-ufs (8.0G) 35653632 16777216 5 freebsd-ufs (8.0G) 52430848 6291456 6 freebsd-ufs (3.0G) 58722304 11628767232 7 freebsd-ufs (5.4T) 11687489536 33555599 - free - (16G) => 34 11721045101 ada1 GPT (5.5T) 34 6 - free - (3.0K) 40 1024 1 freebsd-boot (512K) 1064 984 - free - (492K) 2048 2097152 2 freebsd-ufs (1.0G) 2099200 16777216 3 freebsd-swap (8.0G) 18876416 16777216 4 freebsd-ufs (8.0G) 35653632 16777216 5 freebsd-ufs (8.0G) 52430848 6291456 6 freebsd-ufs (3.0G) 58722304 11628767232 7 freebsd-ufs (5.4T) 11687489536 33555599 - free - (16G) No problems for years. I think your case is somewhat different if you split disk in to 3 partitions later used as 3 devices for one ZFS pool, so maybe there is some coincidence with expanding ZFS... and then it is a bug which should be fixed. Can you prepare some simple testcase (scriptable) which make a panic on your host? I will try it in some spare VM. Miroslav Lachman
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