On Fri, Sep 30, 2016 at 10:52 AM, Dean E. Weimer <dwei...@dweimer.net> wrote:
> On 2016-09-30 9:39 am, Priyadarshan wrote: > >> On Fri, 30 Sep 2016, at 14:34, Dean E. Weimer wrote: >> >>> On 2016-09-29 9:32 am, Dean E. Weimer wrote: >>> > I discovered, unfortunately by deleting a jail by accident, that my >>> > backup process isn't working. At least it was only the operating >>> > system part of the jail, I still have all the data so I just need to >>> > reinstall the operating system. While the ports are in the process of >>> > building I started to investigate the cause, because the backup logs >>> > report everything was fine. >>> > >>> > I have a custom pre-backup script I wrote that takes snapshots of my >>> > ZFS datasets, and then mounts those under /mnt/backup with nullfs >>> > mount points to the .zfs/snapshot/.. directories then I back them up >>> > rather than the live file system, allowing me to stop some services >>> > that don't restore from a running state correctly and then restart >>> > after the snapshot so downtime is only a couple of minutes instead of >>> > full length of backups. >>> > >>> > It appeared to be running perfectly, without errors, but apparently >>> > the script isn't reporting some nullfs mount failures, so why are the >>> > failing, turns out it thinks the file name is too long? but looking at >>> > the mount(2) man page it states this: >>> > >>> > [ENAMETOOLONG] A component of a pathname exceeded 255 characters, >>> > or >>> > the entire length of a path name exceeded 1023 >>> > characters. >>> > >>> > I can see that at some point under this, I may reach that 1023 limit, >>> > but what of the total 71 characters in this path has a problem? >>> > >>> > /jails/unifi/ROOT/.zfs/snapshot/11.0-RELEASE-r306379-2016.09.28--bsnap >>> > >>> > root@freebsd:/jails/unifi/ROOT/.zfs/snapshot # ls >>> > ls: 11.0-RELEASE-r306379-2016.09.28--bsnap: File name too long >>> > >>> > I thought, maybe its a ZFS specific error, and ran across this: >>> > http://lists.freebsd.org/pipermail/freebsd-fs/2010-March/007964.html >>> > >>> > [..snip..] >>> > From looking at the code, I think you hitting this limit: >>> > >>> > /* >>> > * Be ultra-paranoid about making sure the type and fspath >>> > * variables will fit in our mp buffers, including the >>> > * terminating NUL. >>> > */ >>> > if (strlen(fstype) >= MFSNAMELEN || strlen(fspath) >= MNAMELEN) >>> > return (ENAMETOOLONG); >>> > >>> > in vfs_domount() or vfs_donmount(). >>> > >>> > This is FreeBSD limit caused by statfs structure: >>> > >>> > /* >>> > * filesystem statistics >>> > */ >>> > [...] >>> > #define MNAMELEN 88 /* size of on/from name bufs */ >>> > [...] >>> > struct statfs { >>> > [...] >>> > char f_mntfromname[MNAMELEN];/* mounted filesystem */ >>> > char f_mntonname[MNAMELEN]; /* directory on which mounted */ >>> > }; >>> > >>> > When you list .zfs/snapshot/ directory (especially with -l option) ZFS >>> > mounts snapshots on lookup and this is this mount that fails. >>> > [..snip..] >>> > >>> > I can seemingly due anything else with the snapshot, clone, send, >>> > receive its just that I am unable to access the files on it through >>> > .zfs/snapshot/.. >>> > >>> > I am trying to find what the limit is here from this, because this one >>> > here works. >>> > >>> > /jails/webmail/usr-local-subversion/.zfs/snapshot/usr-local- >>> subversion--bsnap >>> > >>> > its longer in total length than most of the ones that are failing. >>> > >>> > /jails/unifi/ROOT/.zfs/snapshot/11.0-RELEASE-r306379-2016.09.28--bsnap >>> > >>> > So it appears that its in the name, and not the mount point. >>> > >>> > this one works as well, which is my ZFS boot environment on the main >>> > system >>> > zraid/ROOT/11.0-RELEASE-r306379-2016.09.28 >>> > snapshot is /.zfs/snapshot/11.0-RELEASE-r306379-2016.09.28--bsnap >>> > >>> > So its not just the last component of the zfs dataset name, which is >>> > in this case the same. >>> > >>> > I am trying to wrap my head around this and find where the limit is so >>> > I can adjust my naming conventions used and actually get backups of >>> > all of my data. Turns out all of my jail operating system paths aren't >>> > being backed up, fortunately at least all of the data file systems for >>> > the jails are. >>> >>> I found a solution, I was naming the snapshots with the dataset name, >>> which I think was causing the issue. >>> >>> The following didn't seem to long to be an issue >>> /jails/unifi/ROOT/.zfs/snapshot/11.0-RELEASE-r306379-2016.09.28--bsnap >>> >>> But apparently the snapshot name was >>> zraid/jails/unifi/11.0-RELEASE-r306379-2016.09.28@11.0- >>> RELEASE-r306379-2016.09.28--bsnap >>> >>> Still not sure how it adds up to too long, both full paths together >>> aren't over 255, at 160, but apparently something else is added in >>> there. I was able to easily modify my backup script to not include the >>> last part of the dataset in the snapshot name and simply use -bsnap-, as >>> the name. it appears to avoid all the issues, and my backups from last >>> night include all the files. >>> >>> /jails/unifi/ROOT/.zfs/snapshot/-bsnap- >>> zraid/jails/unifi/11.0-RELEASE-r306379-2016.09.28@-bsnap- >>> >>> The total path now only adds up to 98, I haven't done any testing yet to >>> find out where the limit is hit, The longest combination of these I had >>> last night would have added up to 135, and that worked >>> >>> -- >>> Thanks, >>> Dean E. Weimer >>> http://www.dweimer.net/ >>> >> >> >> This may be related: >> >> http://iocage.readthedocs.io/en/latest/known-issues.html#cha >> racter-mount-path-limitation >> >> Priyadarshan >> > > Having run into this before in nfs exports , and pulling my hair out; I ran into this fix . I know its from a long time ago; but I am willing to put up a bounty to get this bumped to 512 http://www.secnetix.de/olli/FreeBSD/mnamelen.hawk > Thanks, that's probably it, the original snapshot name with its full data > set path added up to 89, with that in mind I can edit my script to throw a > warning if this limit is hit so that my backup logs will let me know if a > data set gets missed. I need to edit it anyways so that a warning gets > logged on the mount failure which was already occurring. It looks like I > escaped the errors, so that the script returned successful and didn't make > the Bacula backup job fail so that the data that did get mounted would be > backed up, but forgot to write the error to the log. > > -- > Thanks, > Dean E. Weimer > http://www.dweimer.net/ > _______________________________________________ > freebsd-stable@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-stable > To unsubscribe, send any mail to "freebsd-stable-unsubscr...@freebsd.org" > -- mark saad | nones...@longcount.org _______________________________________________ freebsd-stable@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "freebsd-stable-unsubscr...@freebsd.org"
