I access files on our Cray T3E from my Windows 2000 PC via a Samba share.
One of the volumes on the T3E is managed by Cray's Data Migration facility
(DMF). The majority of the DMF files are stored off-line and restored to
disk as necessary. This operation typically takes 3-5 minutes.
Normally when a Windows 2000 application tries to read data from one of the
off-line files--even if it's just the first few bytes--the applications
hangs and then times out after approx. 75 s. This is not a satisfactory
state of affairs because this a frustratingly long length of time but never
long enough to complete the operation. (BTW until you have used a system
like this you might not realise just how often Windows Explorer peeks at the
first few bytes of its files!)
I have been sufficiently motivated recently to do something about this and
have discovered the following registry key...
HKLM\SYSTEM\CurrentControlSet\Services\LanmanWorkstation
\Parameters\SessTimeOut
Setting this to 600 s increases the timeout period sufficiently that read
operations are normally completed successfully. This is an improvement in
some ways, but still frustrating because while a read operation is
pending...
* The reading application hangs and cannot be interrupted (even by the End
Process button in Task Manager)
* No other application on the PC can access the same share.
The latter is especially irritating. It seems as if any given server-client
connection can handle only one transaction at a time. So my question is: is
this a Samba limitation and can it be avoided?
For curiosity's sake I booted the same PC into Linux (RH 7.2) and connected
to the same shares using smbmount. The result is basically the same: if I
try to read data from an off-line file then no other program can access the
same share until the read operation is completed. (I didn't investigate the
time-out period--but it's several minutes--and I didn't investigate
whether
a process that's hung in this way can be killed.)
Sorry I don't have much info about the server's Samba configuration
because
I'm a mere user. But I'm sure my sysadmin could supply any relevant info
if
necessary.
---
Mark Hadfield
m.hadfield@niwa.cri.nz http://katipo.niwa.cri.nz/~hadfield
National Institute for Water and Atmospheric Research
On Fri, Dec 14, 2001 at 04:24:56PM +1300, Mark Hadfield wrote:> > * The reading application hangs and cannot be interrupted (even by the End > Process button in Task Manager) > > * No other application on the PC can access the same share. > > The latter is especially irritating. It seems as if any given server-client > connection can handle only one transaction at a time. So my question is: is > this a Samba limitation and can it be avoided?Yes, this is a Samba limitation. The smbd is stuck in an uninterruptible disk wait in the DMF code. Sorry, Jeremy.