[Gluster-users] I/O error on replicated volume

[Jonathan Heese]

Hello,

So I resolved my previous issue with split-brains and the lack of self-healing by dropping my installed glusterfs* packages from 3.6.2 to 3.5.3, but now I've picked up a new issue, which actually makes normal use of the volume practically impossible.

A little background for those not already paying close attention:
I have a 2 node 2 brick replicating volume whose purpose in life is to hold iSCSI target files, primarily for use to provide datastores to a VMware ESXi cluster.  The plan is to put a handful of image files on the Gluster volume, mount them locally on both Gluster nodes, and run tgtd on both, pointed to the image files on the mounted gluster volume. Then the ESXi boxes will use multipath (active/passive) iSCSI to connect to the nodes, with automatic failover in case of planned or unplanned downtime of the Gluster nodes.

In my most recent round of testing with 3.5.3, I'm seeing a massive failure to write data to the volume after about 5-10 minutes, so I've simplified the scenario a bit (to minimize the variables) to: both Gluster nodes up, only one node (duke) mounted and running tgtd, and just regular (single path) iSCSI from a single ESXi server.

About 5-10 minutes into migration a VM onto the test datastore, /var/log/messages on duke gets blasted with a ton of messages exactly like this:
Mar 15 22:24:06 duke tgtd: bs_rdwr_request(180) io error 0x1781e00 2a -1 512 22971904, Input/output error

And /var/log/glusterfs/mnt-gluster_disk.log gets blased with a ton of messages exactly like this:
[2015-03-16 02:24:07.572279] W [fuse-bridge.c:2242:fuse_writev_cbk] 0-glusterfs-fuse: 635299: WRITE => -1 (Input/output error)

And the write operation from VMware's side fails as soon as these messages start.

I don't see any other errors (in the log files I know of) indicating the root cause of these i/o errors.  I'm sure that this is not enough information to tell what's going on, but can anyone help me figure out what to look at next to figure this out?

I've also considered using Dan Lambright's libgfapi gluster module for tgtd (or something similar) to avoid going through FUSE, but I'm not sure whether that would be irrelevant to this problem, since I'm not 100% sure if it lies in FUSE or elsewhere.

Thanks!

Jon Heese
Systems Engineer
INetU Managed Hosting
P: 610.266.7441 x 261
F: 610.266.7434
www.inetu.net<https://www.inetu.net/>
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