Translate
Open-Mode Locks into HP-UX Advisory Locks |
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The HP CIFS Server A.01.07, and subsequent versions, can translate open
mode locks into HP-UX advisory locks. This functionality prevents HP-UX
processes from obtaining advisory locks on files with conflicting open
mode locks from CIFS clients. This also means CIFS clients cannot open
files that have conflicting advisory locks from HP-UX processes.
You
must change the map share modes setting in smb.conf to yes to translate
open mode locks to HP-UX advisory locks. The default setting of map share modes is no.
Performance
Tuning using Change Notify |
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This section describes performance tuning using the Change
Notify feature and internationalization.
The Samba Server supports a new feature called Change
Notify. Change Notify provides
the ability for a client to request notification from the server
when changes occur to files or subdirectories below a directory
on a mapped file share. When a file or directory which is contained
within the specified directory is modified, the server notifies
the client. The purpose of this feature is to keep the client screen
display up-to-date in Windows Explorer. The result: if a file you
are looking at in Windows Explorer is changed while you are looking
at it, you will see the changes on the screen almost immediately.
The only way to implement this feature in Samba is to periodically
scan through every file and subdirectory below the directory in
question and check for changes made since the last scan. This is
a resource intensive operation which has the potential to affect
the performance of Samba as well as other applications running on
the system. Two major factors affect how resource intensive a scan
is: the number of directories having a Change Notify request on
them, and the size of those directories. If you have many clients
running Windows Explorer (or other file browsers) or if you have
directories on shares with a large number of files and/or subdirectories,
each scan cycle might be very CPU intensive.
To counteract the possible performance impact, you can control
how often Samba scans for changes in the directories it has been
requested to monitor. The parameter that controls how often Samba
scans for changes is Change Notify Timeout. The
parameter value represents the number of seconds between the start
of each scanning cycle. The default value is 60. So, if your system
takes 55 seconds to complete the scan of all the directories with Change
Notify requests, it would be under a heavy load at nearly
all times.You can increase the Change Notify Timeout value
to a larger number to decrease how often these Change
Notify directory scans are done. The trade off is that
your clients will take longer to see that changes
were made in the directories that they have placed Change Notify
requests on. You will have to decide what the right trade-off is:
performance loss or slow updates to client file browsers.
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