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q19sm1414043wra.89.2019.09.05.01.50.07 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 05 Sep 2019 01:50:07 -0700 (PDT) Subject: Re: No files in snapshot To: Oliver Freyermuth , Chris Murphy , Remi Gauvin Cc: linux-btrfs References: <423454bc-aa78-daba-d217-343e266c15ee@georgianit.com> From: Thomas Schneider <74cmonty@gmail.com> Message-ID: Date: Thu, 5 Sep 2019 10:50:06 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org Hi, I would agree with Oliver's conclusion: the relevant directories are all tmpfs mounts. root@ld5505:~# mount | grep /var /dev/sdbq3 on /var/cache type btrfs (rw,noatime,compress=lzo,ssd,space_cache=v2,subvolid=260,subvol=/@cache) /dev/sdbq3 on /var/lib/vz/images type btrfs (rw,noatime,compress=lzo,ssd,space_cache=v2,subvolid=262,subvol=/@images) lxcfs on /var/lib/lxcfs type fuse.lxcfs (rw,nosuid,nodev,relatime,user_id=0,group_id=0,allow_other) tmpfs on /var/lib/ceph/osd/ceph-122 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-123 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-105 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-92 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-112 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-77 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-76 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-87 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-119 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-79 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-115 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-98 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-100 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-89 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-108 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-120 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-82 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-118 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-104 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-95 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-1 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-96 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-117 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-116 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-99 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-106 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-110 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-97 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-81 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-121 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-88 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-0 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-94 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-113 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-107 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-101 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-78 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-93 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-85 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-103 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-102 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-109 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-114 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-80 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-111 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-83 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-86 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-91 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-84 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-90 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-8 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-9 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-10 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-11 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-12 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-13 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-14 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-15 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-16 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-17 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-18 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-19 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-20 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-21 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-22 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-23 type tmpfs (rw,relatime) tmpfs on /var/lib/ceph/osd/ceph-24 type tmpfs (rw,relatime) Am 04.09.2019 um 22:52 schrieb Oliver Freyermuth: > Am 04.09.19 um 21:07 schrieb Chris Murphy: >> On Wed, Sep 4, 2019 at 12:24 PM Remi Gauvin wrote: >>> On 2019-09-04 1:36 p.m., Chris Murphy wrote: >>> >>>> I don't really know how snapper works. >>>> >>>> The way 'btrfs subvolume snapshot' works, you must point it to a >>>> subvolume. It won't snapshot a regular directory and from what you >>>> posted above, there are no subvolumes in /var or /var/lib which means >>>> trying to snapshot /var/lib/ceph/osd/ceph-.... would fail. So maybe >>>> it's failing but snapper doesn't show the error. I'm not really sure. >>>> >>> In this case, his snapshots are all of the root. >>> >>> I don't know how Ceph works, but since we already confirmed that there >>> are no subvolumes under /var, the only other explanation is that >>> /var/lib/ceph/osd/ceph- is a submount >>> >>> What is the the result of running: >>> mount | grep /var >>> >> Yep. >> >> > Looking at Thomas' mail on the Ceph-users list: > http://lists.ceph.com/pipermail/ceph-users-ceph.com/2019-August/036679.html > I deduce he is using Ceph with the Bluestore backend, which indeed means that /var/lib/ceph/osd/ceph. > are tmpfs mounts which are completeley ephemeral and are created from LVM metadata of the actual Ceph OSD disks. > > That would of course also explain why they are not part of any btrfs snapshot of / (and that also means there is no need to backup anything).