Re: File Size and Brick Size

[Ravishankar N <ravishankar@xxxxxxxxxx>]

On 09/28/2016 12:16 AM, ML Wong wrote:

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?

No the checksums must match. Perhaps Krutika who works on Sharding (CC'ed) can help you figure out why that isn't the case here.
-Ravi

[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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