Re: File Size and Brick Size

ML Wong <wongmlb@xxxxxxxxx> · Tue, 27 Sep 2016 11:46:22 -0700

Hello Ravishankar,Thanks for introducing the sharding feature to me.
It does seems to resolve the problem i was encountering earlier. But I have 1 question, do we expect the checksum of the file to be different if i copy from directory A to a shard-enabled volume?

[xxxxx@ip-172-31-1-72 ~]$ sudo sha1sum /var/tmp/oVirt-Live-4.0.4.iso
ea8472f6408163fa9a315d878c651a519fc3f438  /var/tmp/oVirt-Live-4.0.4.iso
[xxxxx@ip-172-31-1-72 ~]$ sudo rsync -avH /var/tmp/oVirt-Live-4.0.4.iso /mnt/
sending incremental file list
oVirt-Live-4.0.4.iso

sent 1373802342 bytes  received 31 bytes  30871963.44 bytes/sec
total size is 1373634560  speedup is 1.00
[xxxxx@ip-172-31-1-72 ~]$ sudo sha1sum /mnt/oVirt-Live-4.0.4.iso
14e9064857b40face90c91750d79c4d8665b9cab  /mnt/oVirt-Live-4.0.4.iso

On Mon, Sep 26, 2016 at 6:42 PM, Ravishankar N <ravishankar@xxxxxxxxxx> wrote:

    On 09/27/2016 05:15 AM, ML Wong wrote:

      Have anyone in the list who has tried copying file
        which is bigger than the individual brick/replica size?
        Test Scenario:
        Distributed-Replicated volume, 2GB size, 2x2 = 4 bricks, 2
          replicas
        Each replica has 1GB

        When i tried to copy file this volume, by both fuse, or nfs
          mount. i get I/O error.

          Filesystem                  Size  Used Avail Use% Mounted
            on
          /dev/mapper/vg0-brick1     1017M   33M  985M   4%
            /data/brick1
          /dev/mapper/vg0-brick2     1017M  109M  909M  11%
            /data/brick2
          lbre-cloud-dev1:/sharevol1  2.0G  141M  1.9G   7%
            /sharevol1

          [xxxxxx@cloud-dev1 ~]$ du -sh
            /var/tmp/ovirt-live-el7-3.6.2.iso 
          1.3G	/var/tmp/ovirt-live-el7-3.6.2.iso

          [melvinw@lbre-cloud-dev1 ~]$ sudo cp
            /var/tmp/ovirt-live-el7-3.6.2.iso /sharevol1/
          cp: error writing ‘/sharevol1/ovirt-live-el7-3.6.2.iso’:
            Input/output error
          cp: failed to extend
            ‘/sharevol1/ovirt-live-el7-3.6.2.iso’: Input/output error
          cp: failed to close
            ‘/sharevol1/ovirt-live-el7-3.6.2.iso’: Input/output error

    Does the mount log give you more information? It it was a disk full
    issue, the error you would get is ENOSPC and not EIO. This looks
    like something else.

        I know, we have experts in this mailing list. And, i
          assume, this is a common situation where many Gluster users
          may have encountered.  The worry i have what if you have a big
          VM file sitting on top of Gluster volume ...?

    It is recommended to use sharding
    (http://blog.gluster.org/2015/12/introducing-shard-translator/) for
    VM workloads to alleviate these kinds of issues.

    -Ravi

        Any insights will be much appreciated.

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