HP Tru64 UNIX and TruCluster Server Version 5.1B-6 Patch Summary and Release Notes

tcp: calls badxids badverfs timeouts newcreds
0 0 0 0 0
creates connects badconns inputs avails interrupts
0 0 0 0 0 0
udp: calls badxids badverfs timeouts newcreds *retrans*
224518870 959 0 101985 0 0
badcalls timers waits
102013 110894 0
Client nfs:
calls * retrans* badcalls nclget nclsleep ndestroys ncleans
224414222 4248 28 224414282 0 6219 224408063 \
If an overwhelmed duplicate request cache condition occurs, we recommend you perform one
or more of the following tasks:
• Ensure that there are short periods of idle time on the I/O subsystem and network links.
• After a file is written, do not rewrite it for a few minutes.
• Delete and recreate files instead of overwriting the same file repeatedly.
• Use Memory Channel cluster interconnect.
To avoid overwhelming the duplicate request cache:
• Do not run hundreds of simultaneous processes that write files
• Do not operate the system under so heavy a load that NFS operations frequently take several
seconds to complete.
Use the netstat command to determine if your network is saturated. For Ethernet networks,
a high number of collisions indicates that the network may be saturated. The following example
shows the output from the netstat -I tu0 command:
Name Mtu Network Address Ipkts Ierrs Opkts Oerrs *Coll*
tu0 1500 <Link xx:xx:xx:xx:xx 840386045 0 254319298 5121 5014223
tu0 1500 network client 840386045 0 254319298 5121 5014223
tu0 1500 DLI none 840386045 0 254319298 5121 5014223
Tuning the NFS Server Duplicate Request Cache
The NFS server maintains a list of recently completed non-repeatable requests. This list is used
to reply to client retransmissions of the request in the event that the initial request transmission's
reply was lost or that the server took too long to satisfy the request.
Problems may occur with the duplicate request cache in some cases, under heavy NFS server
load and over high aggregate network bandwidth involving changes to file systems (changes
caused by the use of the creat, link, unlink, mkdir, rmdir, truncate, utimes,
and write commands). These problems can occur if all the elements in the duplicate request
cache are cycled between an initial client transmission and subsequent retransmission. If this
occurs, the NFS server cannot detect that the retransmission is in fact a retransmission. This may
result in the repetition of a request and may cause out-of-order writes or truncation and
subsequent retruncation of a file.
This patch kit provides a tuning variable, nfs_dupcache_size, to control the size of the NFS
server's duplicate request cache, which is measured in the number of elements that are allocated
at NFS server initialization.
If it is determined that the size of the duplicate cache needs to be modified, you should change
nfs_dupcache_size. The new value for nfs_dupcache_size should be set to equal two
times the value of nfs_dupcache_entries.
You must use the dbx command to modify nfs_dupcache_size. There is no sysconfig interface
to this tuning variable.
Prior Release Notes 53