"Coupal, Chris ISC" wrote:
>
> Greetings,
>
> I have a interesting problem copying large files from a Windows2000 server
> to a SAMBA share. The copy takes extremely long. For example, a 600K file
> takes in excess of 40 seconds. Initially, we had the problem copy the file
> to NT 4 machines as well, but we fixed it with the following work around
> which explains the problem well:
>
> Is there a way we can apply the same "FIX" to samba?
You, sir, are a hero ! I looked at those msdn entries...
It turns out the we didn't understand the implications of
CAP_LARGE_READX/CAP_LARGE_WRITEX very well.
NT normally negotiates a small (4k) buffer, and so sends
very small read/write requests. It uses raw reads/writes
to send larger reads and writes, *BUT ONLY UP TO THE 64k
NetBIOS FRAME SIZE* !
This is a very important thing. Samba *always* offers a
64k buffer size to the client, so there really is no difference
for us between raw and normal reads/writes.
Microsoft "LARGE" read and writes have the capability
to be 32 bit (if you look at the CIFS spec) as they
dedicate a new 16 bit length field on top of the existing
one. However, the NetBIOS frame size prohibits this from
actually being used, so on the wire their "large" read/writes
are just 0xF000 (for safety I guess). Samba can *already*
handle reads and writes of this size as we allocate a
64k buffer anyway.
So..... it turns out all you need to do is apply the
following patch (which I've just applied to the 2.2 and HEAD
sources) - and W2K clients are very fast indeed with a
Samba server :-) :-). It's very simple as all we're doing
is telling W2k clients "hey, we *already* support your large
read/writes" - which we do !
Thanks a *lot* for making me spend the time to look at
this......
Jeremy.
Index: include/smb.h
===================================================================
RCS file: /data/cvs/samba/source/include/smb.h,v
retrieving revision 1.325.2.24
diff -u -r1.325.2.24 smb.h
--- include/smb.h 18 May 2001 20:16:57 -0000 1.325.2.24
+++ include/smb.h 23 May 2001 18:44:43 -0000
@@ -1417,6 +1417,7 @@
#define CAP_NT_FIND 0x0200
#define CAP_DFS 0x1000
#define CAP_LARGE_READX 0x4000
+#define CAP_LARGE_WRITEX 0x8000
#define CAP_EXTENDED_SECURITY 0x80000000
/* protocol types. It assumes that higher protocols include lower protocols
Index: smbd/negprot.c
===================================================================
RCS file: /data/cvs/samba/source/smbd/negprot.c,v
retrieving revision 1.16.4.5
diff -u -r1.16.4.5 negprot.c
--- smbd/negprot.c 8 Mar 2001 14:49:28 -0000 1.16.4.5
+++ smbd/negprot.c 23 May 2001 18:44:44 -0000
@@ -160,6 +160,9 @@
/* dual names + lock_and_read + nt SMBs + remote API calls */
int capabilities = CAP_NT_FIND|CAP_LOCK_AND_READ|CAP_LEVEL_II_OPLOCKS|
(lp_nt_smb_support() ? CAP_NT_SMBS |
CAP_RPC_REMOTE_APIS : 0) |
+#if 1 /* JRATEST */
+ CAP_LARGE_READX | CAP_LARGE_WRITEX
|
+#endif
(SMB_OFF_T_BITS == 64 ? CAP_LARGE_FILES : 0);
--
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