Looks like you might be experiencing this bug:
Fix has been merged to master and I believe it'll be part of infernalis. The original reproducer involved truncating/overwriting files. In your example, do you know if 'kstat' has been truncated/overwritten prior to generating the md5sums?
On Fri, Sep 25, 2015 at 2:11 PM Adam Tygart <mozes@xxxxxxx> wrote:
Hello all,
I've run into some sort of bug with CephFS. Client reads of a
particular file return nothing but 40KB of Null bytes. Doing a rados
level get of the inode returns the whole file, correctly.
Tested via Linux 4.1, 4.2 kernel clients, and the 0.94.3 fuse client.
Attached is a dynamic printk debug of the ceph module from the linux
4.2 client while cat'ing the file.
My current thought is that there has to be a cache of the object
*somewhere* that a 'rados get' bypasses.
Even on hosts that have *never* read the file before, it is returning
Null bytes from the kernel and fuse mounts.
Background:
24x CentOS 7.1 hosts serving up RBD and CephFS with Ceph 0.94.3.
CephFS is a EC k=8, m=4 pool with a size 3 writeback cache in front of it.
# rados -p cachepool get 10004096b95.00000000 /tmp/kstat-cache
# rados -p ec84pool get 10004096b95.00000000 /tmp/kstat-ec
# md5sum /tmp/kstat*
ddfbe886420a2cb860b46dc70f4f9a0d /tmp/kstat-cache
ddfbe886420a2cb860b46dc70f4f9a0d /tmp/kstat-ec
# file /tmp/kstat*
/tmp/kstat-cache: Perl script, ASCII text executable
/tmp/kstat-ec: Perl script, ASCII text executable
# md5sum ~daveturner/bin/kstat
1914e941c2ad5245a23e3e1d27cf8fde /homes/daveturner/bin/kstat
# file ~daveturner/bin/kstat
/homes/daveturner/bin/kstat: data
Thoughts?
Any more information you need?
--
Adam
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