The setup consists of basic afr with performance translators.

client.vol:
==========
volume nwtnhqfarm24.brick
  type protocol/client
  option transport-type tcp/client
  option remote-host 127.0.0.1
  option remote-port 7713
  option remote-subvolume brick
end-volume

volume grnlfarm24.brick
  type protocol/client
  option transport-type tcp/client
  option remote-host 127.0.0.1
  option remote-port 7717
  option remote-subvolume brick
end-volume

volume afr24
  type cluster/afr
  subvolumes nwtnhqfarm24.brick grnlfarm24.brick
end-volume
  
  ## Add writeback feature                                                                                         
volume write-behind_afr24
  type performance/write-behind
  option cache-size 3MB
  option flush-behind on
  subvolumes afr24
end-volume

  ### Add IO-Cache feature                                                                                         
volume iocache_afr24
  type performance/io-cache
  option cache-size 64MB             # default is 32MB                                                             
  option page-size 1MB               #128KB is default option                                                      
  option force-revalidate-timeout 2  # default is 1                                                                
  subvolumes write-behind_afr24
end-volume

  ### Add readahead feature                                                                                        
volume readahead_afr24
  type performance/read-ahead
  option page-count 16
  subvolumes iocache_afr24
end-volume

server-1.vol:
============
volume brick-posix                                                                                                 
  type storage/posix
  option directory /data/raghu/export/1/
end-volume
  

volume brick-posix-locks
  type features/posix-locks
  subvolumes brick-posix
end-volume


volume brick
  type performance/io-threads
  option thread-count 4
  subvolumes brick-posix-locks
end-volume

  
  ### Add network serving capability to above brick.                                                               
volume server
  type protocol/server
  option transport-type tcp/server     # For TCP/IP transport                                                      
  option auth.addr.brick.allow 127.0.0.1,192.168.*
  option listen-port 7713
  subvolumes brick
end-volume

server-2.vol:
============
volume brick-posix
  type storage/posix
  option directory /data/raghu/export/2
end-volume
  

volume brick-posix-locks
  type features/posix-locks
  subvolumes brick-posix
end-volume


volume brick
  type performance/io-threads
  option thread-count 4
  subvolumes brick-posix-locks
end-volume

  
  ### Add network serving capability to above brick.                                                               
volume server
  type protocol/server
  option transport-type tcp/server     # For TCP/IP transport                                                      
  option auth.addr.brick.allow 127.0.0.1,192.168.*
  option listen-port 7717
  subvolumes brick
end-volume

backtrace from gdb reads:
=========================

Core was generated by `glusterfsd -f ./server2.vol -l ./glusterfsd-2.log'.
Program terminated with signal 11, Segmentation fault.
[New process 22910]
[New process 22915]
[New process 22914]
[New process 22913]
[New process 22912]
[New process 22911]
#0  0xb7f7e060 in __glusterfs_this_location@plt () from /usr/lib/libglusterfs.so.0
(gdb) bt
#0  0xb7f7e060 in __glusterfs_this_location@plt () from /usr/lib/libglusterfs.so.0
#1  0xb7f88acf in default_fxattrop (frame=0x8057a88, this=0x80543e8, fd=0x8090910, flags=GF_XATTROP_ADD_ARRAY, 
    dict=0x8090870) at ../../../libglusterfs/src/defaults.c:1122
#2  0xb7f88ac7 in default_fxattrop (frame=0x80908e0, this=0x80548d0, fd=0x8090910, flags=GF_XATTROP_ADD_ARRAY, 
    dict=0x8090870) at ../../../libglusterfs/src/defaults.c:1122
#3  0xb75a6caf in server_fxattrop (frame=0x8059150, bound_xl=0x80548d0, hdr=0x8090948, hdrlen=160, iobuf=0x0)
    at ../../../../../xlators/protocol/server/src/server-protocol.c:4596
#4  0xb75a12d6 in protocol_server_interpret (this=0x8054e58, trans=0x8058730, hdr_p=0x8090948 "", hdrlen=160, 
    iobuf=0x0) at ../../../../../xlators/protocol/server/src/server-protocol.c:7482
#5  0xb75a1483 in protocol_server_pollin (this=0x8054e58, trans=0x8058730)
    at ../../../../../xlators/protocol/server/src/server-protocol.c:7763
#6  0xb75a1503 in notify (this=0x8054e58, event=134544696, data=0x0)
    at ../../../../../xlators/protocol/server/src/server-protocol.c:7819
#7  0xb7f85403 in xlator_notify (xl=0x8054e58, event=2, data=0x8058730) at ../../../libglusterfs/src/xlator.c:820
#8  0xb7faaf08 in socket_event_poll_in (this=0x8058730) at ../../../../transport/socket/src/socket.c:713
#9  0xb7fab261 in socket_event_handler (fd=7, idx=1, data=0x8058730, poll_in=1, poll_out=0, poll_err=0)
    at ../../../../transport/socket/src/socket.c:813
#10 0xb7f9b7a4 in event_dispatch_epoll (event_pool=0x804f1b0) at ../../../libglusterfs/src/event.c:804
#11 0xb7f9a87e in event_dispatch (event_pool=0x804fd38) at ../../../libglusterfs/src/event.c:975
#12 0x0804beb4 in main (argc=5, argv=0xbfd4cd54) at ../../../glusterfsd/src/glusterfsd.c:1223
Current language:  auto; currently asm
(gdb) l    
967     }
968
969     int 
970     main (int argc, char *argv[])
971     {
972             glusterfs_ctx_t  *ctx = NULL;
973             cmd_args_t       *cmd_args = NULL;
974             call_pool_t      *pool = NULL;
975             struct stat       stbuf;
976             char              tmp_logfile[1024] = { 0 };
(gdb) up
#1  0xb7f88acf in default_fxattrop (frame=0x8057a88, this=0x80543e8, fd=0x8090910, flags=GF_XATTROP_ADD_ARRAY, 
    dict=0x8090870) at ../../../libglusterfs/src/defaults.c:1122
1122            STACK_WIND (frame,
Current language:  auto; currently c
(gdb) l
1117                      xlator_t *this,
1118                      fd_t *fd,
1119                      gf_xattrop_flags_t flags,
1120                      dict_t *dict)
1121    {
1122            STACK_WIND (frame,
1123                        default_fxattrop_cbk,
1124                        FIRST_CHILD(this),
1125                        FIRST_CHILD(this)->fops->fxattrop,
1126                        fd,
(gdb) info thr
  6 process 22911  0xb7ea479c in nanosleep () from /lib/libc.so.6
  5 process 22912  0xb7f669de in sem_timedwait () from /lib/libpthread.so.0
  4 process 22913  0xb7f669de in sem_timedwait () from /lib/libpthread.so.0
  3 process 22914  0xb7f669de in sem_timedwait () from /lib/libpthread.so.0
  2 process 22915  0xb7f669de in sem_timedwait () from /lib/libpthread.so.0
* 1 process 22910  0xb7f7e060 in __glusterfs_this_location@plt () from /usr/lib/libglusterfs.so.0


operation being done on mount-point:
===================================
cp -fv ./test.c /mnt/raghu

sometimes it crashed in yyparse@plt. But the crash always seems to be in libglusterfs.so

single client/server configuration works fine.

log file has no interesting contents:
====================================

[2009-06-18 23:10:59] N [server-protocol.c:7035:mop_setvolume] server: accepted client from 127.0.0.1:1020
pending frames:

patchset: git://git.sv.gnu.org/gluster.git
signal received: 11
configuration details:argp 1
backtrace 1
db.h 1
dlfcn 1
fdatasync 1
libpthread 1
llistxattr 1
setfsid 1
spinlock 1
epoll.h 1
xattr.h 1
st_atim.tv_nsec 1
package-string: glusterfs 2.0.0git
[0xffffe420]
/usr/lib/libglusterfs.so.0(default_fxattrop+0xab)[0xb7f0fac7]