[Gluster-users] Sporadic Bus error on mmap() on FUSE mount

[Jan Wrona]

Hi,

I need to use rrdtool on top of a Gluster FUSE mount, rrdtool uses 
memory-mapped file IO extensively (I know I can recompile rrdtool with 
mmap() disabled, but that is just a workaround). I have three FUSE mount 
points on three different servers, on one of them the command "rrdtool 
create test.rrd --start 920804400 DS:speed:COUNTER:600:U:U 
RRA:AVERAGE:0.5:1:24" works fine, on the other two servers the command 
is killed and Bus error is reported. With every Bus error, following two 
lines rise in the mount log:
[2017-07-18 08:30:22.470770] E [MSGID: 108008] 
[afr-transaction.c:2629:afr_write_txn_refresh_done] 0-flow-replicate-0: 
Failing FALLOCATE on gfid 6a675cdd-2ea1-473f-8765-2a4c935a22ad: 
split-brain observed. [Input/output error]
[2017-07-18 08:30:22.470843] W [fuse-bridge.c:1291:fuse_err_cbk] 
0-glusterfs-fuse: 56589: FALLOCATE() ERR => -1 (Input/output error)

I'm not sure about current state of mmap() on FUSE and Gluster, but its 
strange that it works only on certain mount of the same volume.

version: glusterfs 3.10.3

[root at dc1]# gluster volume info flow
Volume Name: flow
Type: Distributed-Replicate
Volume ID: dc6a9ea0-97ec-471f-b763-1d395ece73e1
Status: Started
Snapshot Count: 0
Number of Bricks: 3 x 2 = 6
Transport-type: tcp
Bricks:
Brick1: dc1.liberouter.org:/data/glusterfs/flow/brick1/safety_dir
Brick2: dc2.liberouter.org:/data/glusterfs/flow/brick2/safety_dir
Brick3: dc2.liberouter.org:/data/glusterfs/flow/brick1/safety_dir
Brick4: dc3.liberouter.org:/data/glusterfs/flow/brick2/safety_dir
Brick5: dc3.liberouter.org:/data/glusterfs/flow/brick1/safety_dir
Brick6: dc1.liberouter.org:/data/glusterfs/flow/brick2/safety_dir
Options Reconfigured:
performance.parallel-readdir: on
performance.client-io-threads: on
cluster.nufa: enable
network.ping-timeout: 10
transport.address-family: inet
nfs.disable: true

[root at dc1]# gluster volume status flow
Status of volume: flow
Gluster process                             TCP Port  RDMA Port Online  Pid
------------------------------------------------------------------------------
Brick dc1.liberouter.org:/data/glusterfs/fl
ow/brick1/safety_dir                        49155     0 Y       26441
Brick dc2.liberouter.org:/data/glusterfs/fl
ow/brick2/safety_dir                        49155     0 Y       26110
Brick dc2.liberouter.org:/data/glusterfs/fl
ow/brick1/safety_dir                        49156     0 Y       26129
Brick dc3.liberouter.org:/data/glusterfs/fl
ow/brick2/safety_dir                        49152     0 Y       8703
Brick dc3.liberouter.org:/data/glusterfs/fl
ow/brick1/safety_dir                        49153     0 Y       8722
Brick dc1.liberouter.org:/data/glusterfs/fl
ow/brick2/safety_dir                        49156     0 Y       26460
Self-heal Daemon on localhost               N/A       N/A Y       26493
Self-heal Daemon on dc2.liberouter.org      N/A       N/A Y       26151
Self-heal Daemon on dc3.liberouter.org      N/A       N/A Y       8744

Task Status of Volume flow
------------------------------------------------------------------------------
There are no active volume tasks