I am running the latest Ubuntu 64-bit. When I was using 32-bit, all went ok. When trying to mount a 64-bit, even just after a mklessfs, it failed. The cfg is default, with the exception of the pathnames and the cachesize:2048 MB
Underlying FS is ext4 on an LVM volume. (for both dta & mta)
I had de same issue with 1.0.8.
Hope all this helps.

nice to read this from you, so today i’ve downloaded, compiled, installed this release, but i got a crash.
When i fall back to 1.0.8 lessfs mount again.
Here’s my conf :
DEBUG = 2
HASHLEN = 24
BLOCKDATA_PATH=/home/replication_data/blockdata
BLOCKDATA_BS=112640000
BLOCKUSAGE_PATH=/home/replication_data/blockusage
BLOCKUSAGE_BS=1048576
DIRENT_PATH=/home/replication_data/dirent
DIRENT_BS=1048576
FILEBLOCK_PATH=/home/replication_data/fileblock
FILEBLOCK_BS=1048576
META_PATH=/home/replication_data/meta
META_BS=1048576
HARDLINK_PATH=/home/replication_data/hardlink
HARDLINK_BS=1048576
SYMLINK_PATH=/home/replication_data/symlink
SYMLINK_BS=1048576
FREELIST_PATH=/home/replication_data/freelist
FREELIST_BS=1048576
CACHESIZE=64 #Only 1Gb ram on this test machine
COMMIT_INTERVAL=15
LISTEN_IP=127.0.0.1
LISTEN_PORT=100
MAX_THREADS=2
DYNAMIC_DEFRAGMENTATION=off
COREDUMPSIZE=256000000
SYNC_RELAX=1
ENCRYPT_DATA=off
ENCRYPT_META=off
ENABLE_TRANSACTIONS=on

Here is the gdb output :
gdb /usr/local/bin/lessfs core
GNU gdb (GDB) 7.0-ubuntu
Copyright (C) 2009 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type “show copying”
and “show warranty” for details.
This GDB was configured as “i486-linux-gnu”.
For bug reporting instructions, please see:
…
Reading symbols from /usr/local/bin/lessfs…done.

warning: exec file is newer than core file.
[New Thread 4582]
[New Thread 4584]

warning: Can’t read pathname for load map: Erreur d’entrée/sortie.
Reading symbols from /usr/lib/libmhash.so.2…(no debugging symbols found)…done.
Loaded symbols for /usr/lib/libmhash.so.2
Reading symbols from /usr/local/lib/libtokyocabinet.so.9…done.
Loaded symbols for /usr/local/lib/libtokyocabinet.so.9
Reading symbols from /lib/libbz2.so.1.0…(no debugging symbols found)…done.
Loaded symbols for /lib/libbz2.so.1.0
Reading symbols from /lib/libz.so.1…(no debugging symbols found)…done.
Loaded symbols for /lib/libz.so.1
Reading symbols from /lib/tls/i686/cmov/libpthread.so.0…(no debugging symbols found)…done.
Loaded symbols for /lib/tls/i686/cmov/libpthread.so.0
Reading symbols from /lib/tls/i686/cmov/libm.so.6…(no debugging symbols found)…done.
Loaded symbols for /lib/tls/i686/cmov/libm.so.6
Reading symbols from /lib/tls/i686/cmov/libc.so.6…(no debugging symbols found)…done.
Loaded symbols for /lib/tls/i686/cmov/libc.so.6
Reading symbols from /usr/local/lib/libfuse.so.2…done.
Loaded symbols for /usr/local/lib/libfuse.so.2
Reading symbols from /lib/tls/i686/cmov/librt.so.1…(no debugging symbols found)…done.
Loaded symbols for /lib/tls/i686/cmov/librt.so.1
Reading symbols from /lib/tls/i686/cmov/libdl.so.2…(no debugging symbols found)…done.
Loaded symbols for /lib/tls/i686/cmov/libdl.so.2
Reading symbols from /lib/ld-linux.so.2…(no debugging symbols found)…done.
Loaded symbols for /lib/ld-linux.so.2
Core was generated by `/usr/local/bin/lessfs replication_data/config.cfg -o negative_timeout=0,entry_t’.
Program terminated with signal 11, Segmentation fault.
#0 0xb7582136 in memcpy () from /lib/tls/i686/cmov/libc.so.6

Ok, maybe i did something wrong
Download the 1.1.0 alpha, configure, make, make install, mouting lessfs this way :
/usr/local/bin/lessfs replication_data/config.cfg replication -o negative_timeout=0,entry_timeout=0,attr_timeout=0,use_ino,readdir_ino,default_permissions,allow_other,big_writes,max_read=131072,max_write=131072

Hope this give you some information I’ll accept the following answer :
“your test machine is bullshit” :p

Best regards