About Omneon MediaGrid - Harmonic Inc

System Configuration
If a mount command is issued immediately after loading the omfs module, the command may fail with
an error message indicating, “Some resources could not be allocated, try again later.” Reissue the
mount command later. This message indicates that the omfs module has not completed allocation of
memory after loading.
The Linux FSD does not request any large memory allocations during operation. The memory
allocated at startup must be sufficient to accommodate the file buffer settings. The amount of
memory allocated by the Linux FSD is controlled by the omfs_cache_pre_allocate system control
variable. This parameter can be modified using the following command:
sysctl omfs_cache_pre_allocate=2047
It can also be modified by inserting the following line into the /etc/sysctl.conf file:
omfs_cache_pre_allocate=2047
The value is specified in units of 256KB. The default value is 2047, which is slightly less than 512MB.
On a computer with 1GB RAM there will be 512MB left for other system operations.
The Linux FSD will not release any memory it has acquired. Reducing the
omfs_cache_pre_allocate value after memory has been allocated has no effect. Since the Linux
FSD begins allocating memory as soon as the omfs module is loaded by the Linux kernel, trying to
limit the amount of memory allocated to a value below 512MB using this method produces
inconsistent results.
To limit the memory usage to below 512MB, use the cachePreAllocLimit module load parameter.
For example, when loading the omfs module with the modprobe command use the following format:
modprobe omfs cachePreAllocLimit=40
The example above limits the Linux FSD to using only 10MB for cache memory. This parameter may
also be used in the /etc/modprobe.conf configuration file.
Specifying Buffer Memory for Windows Clients
To configure the amount of memory used for ReadAhead buffering, refer to Setting Windows FSD
Parameters. The memory used is specified in units of slices.
For example, if each slice is 8MB in size, setting ReadAhead=2 would consume 16MB of memory for
each active file. The default value is ReadAhead=3.
To configure the amount of memory used for cache memory limit:
IMPORTANT: The following procedure involves modifying the Windows registry. If you are unsure of the
changes, please contact Omneon Technical Support for assistance.
The default limit for the MaximumCacheSize value is four times that of the InitialcacheSize, which is
calculated based on system physical memory size.
1. Start the regedit.exe program. (If the computer does not fully boot, boot in safe mode first).
2. Navigate to the following registry location:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\OmRdr\Parameters
3. Create a DWORD value in the above registry key with the name cacheMaxMem.
134 Installation and Configuration Guide