Date: Tue, 22 Sep 2015 08:15:05 +0000 From: Matt Churchyard <matt.churchyard@userve.net> To: Chris Stankevitz <chris@stankevitz.com> Cc: FreeBSD FS <freebsd-fs@freebsd.org> Subject: RE: Name/label/id metadata: how do I make it go away Message-ID: <e1abb521ab324532b3445d26984f5638@SERVER.ad.usd-group.com> In-Reply-To: <5600F0DF.8000805@stankevitz.com> References: <56004C68.4020904@stankevitz.com> <alpine.BSF.2.20.1509212126470.4544@wonkity.com> <5600F0DF.8000805@stankevitz.com>
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>Warren/Freddie, >Thank you for your replies. >On 9/21/15 8:41 PM, Warren Block wrote: >>> - gpt id >> >> A system-assigned ID in the GPT metadata. Requires GPT partitioning. >>> I have a zfs pool of "entire disks". "zpool status" shows some disks=20 >>> with their daX name (which I prefer) and some with a hideously ugly=20 >>> name such as DISK-%20%20%20%20%20-WD-WMC4NOH1ASDF >> >> Disable those labels with kern.geom.label.gptid.enable=3D"0" in=20 >> /boot/loader.conf. >Combining your two statements quoted above, I believe I can conclude that = my ZFS "whole disk" drives must have some remnants of GPT left >over from t= heir previous lives (namely the system-assigned ID in the GPT metadata). >Surprisingly, these apparently GPT-supplied labels appear to "go away"=20 >when I issue a "glabel stop". I would not expect this given that Warren e= xplained that glabels (whose metadata are stored at the end of the >device = and completely outside the virtual device) are not the same as GPT labels (= whose metadata are stored within the device on the GPT >metadata). >I believe one of the following must be true: >1. It is possible to use "glabel stop" to disable a "GPT system-assigned I= D" -- even though glabel is a tool for manipulating another style of labels= . >2. "glabel stop" only affects glabels. In my case my drives must contain = "glables" and not "GPT system-assigned IDs" as Warren guessed. >3. I misunderstood and glabels/GPS system-assigned IDs are really the same= thing. >Thank you again, >Chris The diskid entries have nothing to do with GPT. I suspect your disks do not= have any partitioning. These labels are generated automatically based on t= he actual vendor supplied ID for each disk. The glabel command allows you to assign a label to a GEOM device, which wil= l then appear as /dev/label/name. I personally dislike these as they are no= t portable and are one block smaller than the original device, which is sti= ll accessible. It appears glabel is also responsible for identifying various other "labell= ing" methods that weren't necessary created using the utility. For instance= it will create /dev/ufsid/X devices, where X is the ID of a UFS filesystem= it has found on a GEOM device. It also seems to be responsible for creatin= g /dev/gpt entries as well as /dev/diskid, which is possibly why they disap= pear when you run glabel stop. Most of this is mentioned in the man page, a= lthough it doesn't mention the diskid entries; There does however appear to= be a geom/label/g_label_disk_ident.c source file which implements the /dev= /diskid/X functionality. The thing to be clear on is that although glabel is responsible for creatin= g the device nodes for most of these labels, the way they are assigned is v= ery different=20 diskid - Automatic based on the ID of the disk - so should reference an ent= ire disk gpt - Assigned manually to a partition by GPT partitioning a disk and creat= ing labelled partitions gptid - Automatic when you partition a disk with GPT and create partitions = (every GPT partition has a unique GUID) glabel - Assigned to any disk or partition manually by using the glabel com= mand Interestingly, looking though sysctl, I see options to turn off most label = devices, but nothing mentions diskid. I don't know if this is actually mis= sing, or if one of the existing sysctls also turns them off. (Surely there = should ideally be a kern.geom.label.diskid.enable?) kern.geom.label.ext2fs.enable: 1 kern.geom.label.iso9660.enable: 1 kern.geom.label.msdosfs.enable: 1 kern.geom.label.ntfs.enable: 1 kern.geom.label.reiserfs.enable: 1 kern.geom.label.ufs.enable: 1 kern.geom.label.ufsid.enable: 1 kern.geom.label.gptid.enable: 1 kern.geom.label.gpt.enable: 1 Regards, Matt Churchyard
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