Date: Sun, 6 Sep 2015 17:54:57 +0200 From: Johan Hendriks <joh.hendriks@gmail.com> To: freebsd-fs@freebsd.org Subject: Re: can zfs snapshot be used to back LUN in ctl.conf ? Message-ID: <55EC61D1.6010206@gmail.com> In-Reply-To: <55EC4F3B.7090804@digiware.nl> References: <20150827150027.10825@smtp.new-ukraine.org> <55EC4F3B.7090804@digiware.nl>
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Op 06/09/15 om 16:35 schreef Willem Jan Withagen: > On 27-8-2015 14:00, Zeus Panchenko wrote: >> greetings, >> >> please help me to understand where to look at ... >> >> recently I switched from istgt to ctld and now wonder, whether can zfs >> snapshot be used to back the LUN for ctld? >> >> istgt do allows that, while ctld fails to start and complains >> >> but if I copy the file from zfs snapshot to some place, then ctld starts >> as expected ... > As far as I know those snapshots are read-only. > > So other that mount and use for reading backup stuff it does not really > serve a purpose? And than still you'd next a "consistent" fs on the > volume to do any useful work. So that would only work for filesystems > that need a recover that does not involve writing to the volume. > Otherwise if you force mount something like UFS, you run the risk of > crashes? > > So unless you promote a the volume to writable things will not work. > For files as backing volume that happens if you copy it to a writeable > location, or clone the volume the file is on. If you are using ZVOL, > than you have to clone snapshot. > > So I'm not sure if ctld aborts because it tests writing the backing > storage and fails if it cannot. > > --WjW I just noticed something beeing mentioned on freshbsd.org. mav <http://freshbsd.org/search?committer=mav&project=freebsd>; @ HEAD <http://freshbsd.org/search?branch=HEAD&project=freebsd>; - r287499 <http://freshbsd.org/commit/freebsd/r287499>; - 2015 <http://freshbsd.org/2015>-09 <http://freshbsd.org/2015/09>-06 <http://freshbsd.org/2015/09/06>; 09 <http://freshbsd.org/2015/09/06/09>:54 <http://freshbsd.org/2015/09/06/09/54>:56 <http://freshbsd.org/2015/09/06/09/54/56>; Move setting of media parameters inside open routines. This is preparation for possibility to open/close media several times per LUN life cycle. While there, rename variables to reduce confusion. As additional bonus this allows to open read-only media, such as ZFS snapshots. So I think in HEAD it should be possible from now on after revision 287499 gr Johan >> >> bellow the details are: >> >> ---[ ctld debug quotation start ]------------------------------------------- >> ... >> ctld: adding lun 0, target iqn.2007-09.jp.ne.peach.istgt:file011 >> ctld: adding lun 0, target iqn.2007-09.jp.ne.peach.istgt:file012 >> ctld: error returned from LUN creation request: ctl_be_block_open: error opening /storage/win/.zfs/snapshot/daily-2015-08-22/file013 >> ctld: failed to add lun 0, target iqn.2007-09.jp.ne.peach.istgt:file013 >> ctld: adding lun 0, target iqn.2007-09.jp.ne.peach.istgt:file014 >> ctld: adding lun 0, target iqn.2007-09.jp.ne.peach.istgt:file015 >> ... >> ctld: adding lun 0, target iqn.2007-09.jp.ne.peach.istgt:file052 >> ctld: adding lun 0, target iqn.2007-09.jp.ne.peach.istgt:file053 >> ctld: not listening on portal-group "default", not assigned to any target >> ctld: listening on 10.100.21.47, portal-group "alfa" >> ctld: listening on 10.100.21.47, portal-group "beta" >> ctld: failed to apply configuration; exiting >> /etc/rc.d/ctld: WARNING: failed to start ctld >> ---[ ctld debug quotation end ]------------------------------------------- >> >> ---[ ctl.conf quotation start ]------------------------------------------- >> target iqn.2007-09.jp.ne.peach.istgt:file013 { >> alias "file013-users" >> portal-group alfa >> auth-group ag-file013 >> lun 0 { >> path /storage/win/.zfs/snapshot/daily-2015-08-22/file013 >> size 300G >> } >> } >> ---[ ctl.conf quotation end ]------------------------------------------- >> >> the very file exists: >>> stat /storagez/win/.zfs/snapshot/daily-2015-08-22/traders.ts.ibs >> 3500296891 22 -rw-r--r-- 1 root wheel 4294967295 214748364800 "Oct 23 07:41:38 2013" "Aug 21 04:00:28 2015" "Aug 21 04:00:28 2015" "Oct 23 07:41:38 2013" 131072 419838466 0x800 /storage/win/.zfs/snapshot/daily-2015-08-22/file013 >> >> >> another question: can ctld be configured to ignore unavailable config >> parts? like unaccessible/missconfigured LUNs > _______________________________________________ > freebsd-fs@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-fs > To unsubscribe, send any mail to "freebsd-fs-unsubscribe@freebsd.org"
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