Date: Mon, 17 Jan 2011 14:30:43 +0100 From: Ivan Voras <ivoras@freebsd.org> To: freebsd-geom@freebsd.org Subject: Re: Broken gmirror: why /dev/ufs is empty when geom_mirror is not loaded? Message-ID: <ih1ga3$tdv$1@dough.gmane.org> In-Reply-To: <1811347380.20110113213700@serebryakov.spb.ru> References: <1686083494.20110113182418@serebryakov.spb.ru> <1811347380.20110113213700@serebryakov.spb.ru>
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On 13/01/2011 19:37, Lev Serebryakov wrote: > Hello, Freebsd-geom. > You wrote 13 января 2011 г., 18:24:18: > >> I have mirrored PARTITION (/dev/ad4s1d + /dev/ad6s1d) with UFS with >> label on it. This label is shown in /dev/ufs when geom_mirror is >> loaded. > >> When geom_mirror is NOT loaded both ad4s1d and ad6s1d are valid, >> complete, clean filesystems, but here is no /dev/ufs entries for them, >> and kernel can not mount FSes at all. > And even worse: it sees ONE of all FSes and when "geom_mirror" is > loaded, it puck up one of components from "/dev/ufs/home" instead of > device node and everything hangs up due to loop (?)... Yes, gmirror and glabel are known to interact badly because of such edge cases - since glabel presents the whole underlying device in pretty much the same way as the original device entry, gmirror cannot distinguish between the two. You could use the "-h" argument to "gmirror create" to get around this. Since this is so common and has also bitten me in the past, I wonder if some kind of avoidance detection mechanism could be created in gmirror? I'm thinking of making glabel expose a GEOM property like "fslabel" meaning "this device entry comes from a file system label, not a device or native glabel label" and making gmirror search for this property and skip tasting for devices having it? Pawel?
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