HP StorageWorks Enterprise File Services WAN Accelerator 2.1.7 Deployment Guide (407118 - 003, June 2006)

128 11 - TROUBLESHOOTING DEPLOYMENT PROBLEMS
Similar
Problems
See also these similar problems:
 “Problem: Old Anti-Virus Software” on page 124
 “Problem: Unavailable Opportunistic Locks” on page 128
Problem: Unavailable Opportunistic Locks
If a file is not optimized for more than one user at a time, it could be because an
application’s lock on it prevents other applications and the HP EFS WAN Accelerator
from obtaining exclusive access to the file. Without an exclusive lock, the HP EFS
WAN Accelerator cannot perform latency (for example, read-ahead, write-behind, and
so forth) optimization on the file.
Without opportunistic locks (oplocks), SDR and compression are still performed on
file contents, but the HP EFS WAN Accelerator cannot perform latency optimization
because data integrity cannot be ensured without exclusive access to the file data.
The following are symptoms of unavailable oplocks:
 Within a WAN:
 A client, PC1, in a remote office across the WAN can open a file it previously
opened in just a few seconds.
 Another client, PC2, on the WAN has also previously opened the file but
cannot open it quickly while PC1 has it open. While PC1 has the file open, it
takes PC2 significantly longer to open the file.
 When PC1 closes the file, PC2 can once again open it quickly. However, while
PC2 has the file open, PC1 cannot open it quickly; it takes significantly longer
for PC1 to open the file while PC2 has it open.
 If no client has the file open and PC1, PC2, and a third client on the WAN
(PC3) simultaneously copy, but do not open the file, each client can copy the
file quickly and in nearly the same length of time.
 The results of a tcpdump show that WAN utilization is low for files that take a
long time to open.
 In the Management Console, slow connections appear optimized.
TIP: You can check a connection’s bandwidth reduction in the Management Console.
Solution: None
Needed
To prevent any compromise to data integrity, the HP EFS WAN Accelerator only
accelerates access to data to which exclusive access is available. When unavailable
oplocks prevent the HP EFS WAN Accelerator from performing latency optimization,
the HP EFS WAN Accelerator still performs SDR and compression on the data.
Therefore, even without the benefits of latency optimization, HP EFS WAN
Accelerators may still increase WAN performance, but not as effectively as when
application optimizations are available.