Date: Fri, 28 Nov 2014 12:21:05 +0100 From: Lorenzo Perone <lopez.on.the.lists@yellowspace.net> To: freebsd-fs@freebsd.org Subject: Mounting a filesystem on a HAST provider without HAST (was: Re: HAST, zvols, istgt and carp working...) Message-ID: <54785AA1.10107@yellowspace.net> In-Reply-To: <5477B7AF.5020802@yellowspace.net> References: <AANLkTim5FRJkf_S0aSV74S=JY%2Bg1DBZLhjYW7X9C0MkP@mail.gmail.com> <5477B7AF.5020802@yellowspace.net>
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Hi All, I succeeded on this topic, but a new question arose - so I'd like to share the (provisory) solution as well as the question... On 28.11.14 00:45, Lorenzo Perone wrote: > Is there any way to mount the snapshot [of a provider used by hast] read only - or to have a 'hast' > wrapper for the snapshot without having to really 'hast' it? I was able to succeed after comparing a hexdump of the first few MBs of the original zvol and the vol "under hast". ( /dev/zvol/rtank/vols/jail1@hellotest vs. /dev/hast/jail1 ) The UFS filesystem on the zvol provider begins after 135168 bytes (132KB) of hast-header. So I tried to create a transparent provider with gnop: gnop create -o 135168 /dev/zvol/rtank/vols/jail1@hellotest and the mount mount -t ufs -o ro /dev/zvol/rtank/vols/jail1@hellotest.nop /mnt succeeded. Now my new question is: Can I "safely" assume that this header is always 132K (I assume not - it probably contains the bitmap...)? In this case, which formula should be applied to calculate the offset? Thanks a lot in advance for any hint, And to the FreeBSD team / pjd: THANKs for GEOM! :-) It really is the best invention closely after espresso coffee... Gretings and Regards,
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