HP StorageWorks Enterprise File Services WAN Accelerator 3.0.4 deployment guide (AG421-96001, March 2007)

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HP STORAGEWORKS ENTERPRISE FILE SERVICES WAN ACCELERATOR DEPLOYMENT GUIDE 129

13 - TROUBLESHOOTING

EPLOYMENT PROBLEMS

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 it. 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 performed on file

contents, but the HP EFS WAN Accelerator cannot perform latency optimization

because data integrity cannot be ensured without exclusive access to 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.

Similar

Problems