Riverbed SteelHead 5080, Руководство по установке и настройке

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50 | Troubleshooting
CIFS overlapping open optimization denies multi-user access
Example
You can open a previously accessed file in 5 seconds on PC1, but you can’t open the same file under 24
seconds on PC2. If you close the file on PC1, you can open it in 5 seconds on PC2. However, it takes you
24 seconds to open the same file on PC1.
Solutions
Windows Common Internet File System (CIFS) uses oplock to determine the level of safety the OS or the
application has in working with a file. Oplock is a lock that a client requests on a file in a remote server.
An oplock controls the consistency of optimizations such as read-ahead. Oplock levels are reduced
when you make conflicting opens to a file.
To prevent any compromise to data integrity, the SteelHead only optimizes data when a client has
exclusive access to the data.
When an oplock is not available, the SteelHead doesn’t perform application-level latency optimization
but still performs scalable data referencing (SDR) and data compression as well as TCP optimization.
Therefore, even without the benefits of latency optimization, SteelHeads still increase WAN
performance, but not as effectively as when application optimizations are available.
To resolve oplock issues:
• Upgrade your antivirus software to the latest version.
• Use Filemon (sysinternals) to check for file access.
• Enable CIFS Overlapping Opens (by default, this function is enabled). For details, see “CIFS
overlapping open optimization denies multi-user access” on page 50 .
• Ensure that the server has oplock enabled by verifying registry settings on Windows servers or the
Filer configuration (for NetApp or EMC servers).
• Run a network analyzer such as Riverbed SteelCentral Packet Analyzer Plus, which is fully integrated
with Wireshark, and determine that the server grants oplocks when the client opens a file.
• Check whether the client is running an antivirus software that is scanning the files over the WAN or
that the antivirus software doesn’t break the oplock.
CIFS overlapping open optimization denies multi-user access
The CIFS overlapping open optimization issue prevents a client from accessing a file when different
clients access the file at the same time.
Solution
To resolve the CIFS overlapping open optimization issue, configure CIFS overlapping open optimization
on the client-side SteelHead as follows:
1. Connect to the SteelHead Management Console.