Hi John and Zheng,
Thanks for the quick replies!
I'm using kernel 4.2. I'll test out that fix.
Arthur
On Wed, Sep 2, 2015 at 10:29 PM, Yan, Zheng <ukernel@xxxxxxxxx> wrote:
probably caused by http://tracker.ceph.com/issues/12551
On Wed, Sep 2, 2015 at 7:57 PM, Arthur Liu <arthurhsliu@xxxxxxxxx> wrote:
> Hi,
>
> I am experiencing an issue with CephFS with cache tiering where the kernel
> clients are reading files filled entirely with 0s.
>
> The setup:
> ceph 0.94.3
> create cephfs_metadata replicated pool
> create cephfs_data replicated pool
> cephfs was created on the above two pools, populated with files, then:
> create cephfs_ssd_cache replicated pool,
> then adding the tiers:
> ceph osd tier add cephfs_data cephfs_ssd_cache
> ceph osd tier cache-mode cephfs_ssd_cache writeback
> ceph osd tier set-overlay cephfs_data cephfs_ssd_cache
>
> While the cephfs_ssd_cache pool is empty, multiple kernel clients on
> different hosts open the same file (the size of the file is small, <10k) at
> approximately the same time. A number of the clients from the OS level see
> the entire file being empty. I can do a rados -p {cache pool} ls for the
> list of files cached, and do a rados -p {cache pool} get {object} /tmp/file
> and see the complete contents of the file.
> I can repeat this by setting cache-mode to forward, rados -p {cache pool}
> cache-flush-evict-all, checking no more objects in cache with rados -p
> {cache pool} ls, resetting cache-mode to writeback with an empty pool, and
> doing the multiple same file opens.
>
> Has anyone seen this issue? It seems like what may be a race condition where
> the object is not yet completely loaded into the cache pool so the cache
> pool serves out an incomplete object.
> If anyone can shed some light or any suggestions to help debug this issue,
> that would be very helpful.
>
> Thanks,
> Arthur
>
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