On 11/13/19 2:42 AM, Gregory Farnum wrote:
On Tue, Nov 12, 2019 at 6:39 AM Toby Darling <toby@xxxxxxxxxxxxxxxxx> wrote:
Hi Folks
I'm writing a backup/sync process for our ceph cluster. The process
takes a snapshot of the system that's being backed up and rsync's from
that to another ceph cluster
I was hoping to use the snapshot xattrs to verify a successful backup by
comparing ceph.dir.rbytes and ceph.dir.rentries between the snapshot and
backup target.
However, while files added to the source directory after the snapshot is
taken don't appear in the snapshot, ceph.dir.rbytes and ceph.dir.rctime
are updated in the xattrs of both.
I don't remember for sure, but I think you're falling victim to rstat
propagation being lazy here, and metadata in snapshots being somewhat
delayed. Can you try doing a sync before you take the snapshot and see
if that changes the behavior?
-Greg
yes, rstats in snapshot are not reliable. you'd better to another method
to verify your backup.
Yan, Zheng
$ fallocate -l 1K test1
$ getfattr -n ceph.dir.rbytes .
# file: .
ceph.dir.rbytes="1024"
$ mkdir .snap/testsnap
$ fallocate -l 2K test2
$ getfattr -n ceph.dir.rbytes . .snap/testsnap
# file: .
ceph.dir.rbytes="3072"
# file: .snap/testsnap
ceph.dir.rbytes="3072"
$ getfattr -n ceph.dir.rctime . .snap/testsnap
# file: .
ceph.dir.rctime="1573558448.09736131125"
# file: .snap/testsnap
ceph.dir.rctime="1573558448.09736131125"
$ tree -a --si . .snap
.
|-- [1.0k] test1
`-- [2.0k] test2
.snap
`-- [3.1k] testsnap
`-- [1.0k] test1
1 directory, 3 files
Have I misunderstood? Is this expected behaviour?
Cheers
Toby
--
Toby Darling, Scientific Computing (2N249)
MRC Laboratory of Molecular Biology
Francis Crick Avenue
Cambridge Biomedical Campus
Cambridge CB2 0QH
Phone 01223 267070
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