Gordan Bobic wrote:
With native NFS there'll be no need to first mount a glusterFS
FUSE based volume and then export it as NFS. The way it has been
developed is that
any glusterfs volume in the volfile can be exported using NFS by adding
an NFS volume over it in the volfile. This is something that will become
clearer from the sample vol files when 3.0.1 comes out.
It may be worth checking the performance of that solution vs the
performance of the standalone unfsd unbound to portmap/mountd over
mounted glfs volumes, as I discovered today that the performance feels
very similar to native knfsd and server-side AFR, but without the
fuse.ko complications of the former and the buggyness of the latter
(e.g. see bug 186:
http://bugs.gluster.com/cgi-bin/bugzilla3/show_bug.cgi?id=186 - that bug
has been driving me nuts since before 2.0.0 was released)
I'd hate to see this be another wasted effort like booster when there is
a solution that already works.
The answer to your question is, yes, it will be possible to export your
local file system with knfsd and glusterfs distributed-replicated volumes
with Gluster NFS translator BUT not in the first release.
See comment above. Isn't that all the more reason to double check
performance figures before even bothering?
In fact, I may have just convinced myself to acquire some iozone
performance figures. Will report later.
OK, I couldn't get iozone to report sane results. glfs was reporting
things in the reasonable ball park I'd expect (between 7MB/s and 110MB/s
which is what I'd expect on gigabit ethernet). NFS was reporting figures
that look more like the memory bandwidth so I'd guess that FS-Cache was
taking over. With O_DIRECT and O_SYNC figures were in the 700KB/s range
for NFS which is clearly not sane because in actual use the two seem
fairly equivalent.
So - I did a redneck test instead - dd 64MB of /dev/zero to a file on
the mounted partition.
On writes, NFS gets 4.4MB/s, GlusterFS (server side AFR) gets 4.6MB/s.
Pretty even.
On reads GlusterFS gets 117MB/s, NFS gets 119MB/s (on the first read
after flushing the caches, after that it goes up to 600MB/s). The
difference in the unbuffered readings seems to be in the sane ball park
and the difference on the reads is roughly what I'd expect considering
NFS is running UDP and GLFS is running TCP.
So in conclusion - there is no performance difference between them worth
speaking of. So what is the point in implementing a user-space NFS
handler in glusterfsd when unfsd seems to do the job as well as
glusterfsd could reasonably hope to?
There is, however a problem iozone showed up - it wouldn't complete on
glfs. The glusterfs client would cause it to error out before it
finished. iozone would report errors like this:
Error writing block 2047, fd= 3
write: Transport endpoint is not connected
Error writing block 2047, fd= 3
write: File descriptor in bad state
Error writing block 2047, fd= 3
write: File descriptor in bad state
/home/gordan/test/f1: Transport endpoint is not connected
/home/gordan/test/f2: Transport endpoint is not connected
/home/gordan/test/f3: Transport endpoint is not connected
/home/gordan/test/f4: Transport endpoint is not connected
On the client, the logs show things like this:
[2010-01-06 21:42:30] E
[client-protocol.c:457:client_ping_timer_expired] home: Server
10.2.0.10:7000 has not responded in the last
10 seconds, disconnecting.
[2010-01-06 21:42:30] E [saved-frames.c:165:saved_frames_unwind] home:
forced unwinding frame type(1) op(FSYNC)
[2010-01-06 21:42:30] W [fuse-bridge.c:888:fuse_err_cbk] glusterfs-fuse:
269780: FSYNC() ERR => -1 (Transport endpoint is not connec
ted)
Followed by lots of this:
[2010-01-06 21:46:39] W [fuse-bridge.c:1540:fuse_writev_cbk]
glusterfs-fuse: 532985: WRITE => -1 (Transport endpoint is not connecte
d)
and this:
[2010-01-06 21:53:41] W [fuse-bridge.c:888:fuse_err_cbk] glusterfs-fuse:
537456: FLUSH() ERR => -1 (File descriptor in bad state)
glfs seems to be rather fragile when load starts approaching wire speed.
My ssh sessions running top to the same machine didn't disconnect or
show any noticeable lag, so the disconnections are probably uncalled for
- there ought to be a more graceful way to deal with it. How often does
it send heartbeat packets and how many in a row have to go missing
before it decided to disconnect?
Another thing I noticed is that even though the server glusterfs process
was running with it's server side AFR export, the first time I tried to
connect to it from the client after some hours of using the NFS mount,
the server process appears to have crashed. This was what ended up in
it's log:
[2010-01-06 21:35:54] N [server-protocol.c:7065:mop_setvolume]
server-home: accepted client from 10.2.3.1:1023
[2010-01-06 21:35:54] N [server-protocol.c:7065:mop_setvolume]
server-home: accepted client from 10.2.3.1:1022
pending frames:
frame : type(1) op(LOOKUP)
frame : type(1) op(LK)
patchset: v2.0.9
signal received: 11
time of crash: 2010-01-06 21:36:12
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 2.0.9
/lib64/libc.so.6[0x3f55e302d0]
/usr/lib64/glusterfs/2.0.9/xlator/protocol/client.so(client_lookup+0xc8)[0x2afea8f89438]
/usr/lib64/glusterfs/2.0.9/xlator/cluster/replicate.so(afr_lookup+0x226)[0x2afea97e3e66]
/usr/lib64/glusterfs/2.0.9/xlator/protocol/server.so(server_lookup_cbk+0x513)[0x2afea95cb2a3]
/usr/lib64/glusterfs/2.0.9/xlator/cluster/replicate.so(afr_self_heal_cbk+0x8e)[0x2afea97e46fe]
/usr/lib64/glusterfs/2.0.9/xlator/cluster/replicate.so(afr_sh_data_done+0xbe)[0x2afea97f8bce]
/usr/lib64/glusterfs/2.0.9/xlator/cluster/replicate.so(afr_sh_data_flush_cbk+0x44)[0x2afea97fa284]
/usr/lib64/glusterfs/2.0.9/xlator/cluster/replicate.so(afr_sh_data_utimes_cbk+0x9)[0x2afea97fa2a9]
/usr/lib64/glusterfs/2.0.9/xlator/protocol/client.so(client_utimens_cbk+0x14e)[0x2afea8f9152e]
/usr/lib64/glusterfs/2.0.9/xlator/protocol/client.so(protocol_client_pollin+0xca)[0x2afea8f808aa]
/usr/lib64/glusterfs/2.0.9/xlator/protocol/client.so(notify+0x212)[0x2afea8f874e2]
/usr/lib64/glusterfs/2.0.9/transport/socket.so(socket_event_handler+0xd3)[0x2aaaaaaafe33]
/usr/lib64/libglusterfs.so.0[0x3f56a27115]
/usr/sbin/glusterfs(main+0xa06)[0x403e96]
/lib64/libc.so.6(__libc_start_main+0xf4)[0x3f55e1d994]
/usr/sbin/glusterfs[0x402509]
---------
None of the above went wrong when using the unfsd mount - and that
really doesn't look very confidence inspiring in a stable release (2.0.9).
Gordan
