Tunable parameters for VVR


Tunable parameters for VVR
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Table: VVR Tunables lists the tunable parameters for VVR.

You can tune the parameters using SMIT or using the vxtune command. The table displays the name of the tunable as shown in SMIT followed by the name as used by the vxtune command. If no SMIT name is displayed, you must use the vxtune command to change the tunable.

Table: VVR Tunables

Tunable Name	Description
vol_cmpres_enabled	A per-system tunable parameter that enables or disables compression globally. The default value is 0, since compression is disabled by default.
vol_cmpres_threads	A per-system tunable that lets you set the number of compression threads on the Primary host or the number of decompression threads on the Secondary host between 1 and 64. The default value is 10. You can tune this setting dependent on your CPU usage.
Maximum size per message for resync or autosync vol_dcm_replay_size	This tunable cannot be changed using the vxtune command. The size of the DCM replay blocks. The default value is 256KB.
Maximum memory allocated for VVR nmcom pool vol_max_nmpool_sz	The amount of buffer space available for requests coming in to the Secondary over the network. The default value is 64MB.
Maximum memory allocated for VVR readback pool vol_max_rdback_sz	The amount of buffer space available for readbacks. The default value is 128MB.
vol_max_wrspool_sz	The write ship buffer space, which is the amount of buffer space that can be allocated on the logowner to receive writes sent by the non-logowner. The default value is 64MB.
Minimum Threshold for in-memory updates vol_min_lowmem_sz	The minimum buffer space. VVR frees the write if the amount of buffer space available is below this threshold. The default value is about 520 kilobytes, twice the size of a maximum write. This value is auto-tunable. The value that you specify is used as an initial value and could change depending on the application write behavior.
vol_nm_hb_timeout	The heartbeat timeout value. The default value is 10 seconds.
Maximum memory allocated for VVR I/O pool vol_rvio_maxpool_sz	The amount of buffer space that can be allocated within the operating system to handle incoming writes. The default value is 128MB.
Replication over NAT based Firewall vol_vvr_use_nat	This tunable cannot be changed using the vxtune command. This tunable parameter directs VVR to use the translated address from the received message so that VVR can communicate over a NAT-based firewall. Set this tunable to 1 only if there is a NAT-based firewall in the configuration.

Tunable Name

Description

vol_cmpres_enabled

A per-system tunable parameter that enables or disables compression globally. The default value is 0, since compression is disabled by default.

vol_cmpres_threads

A per-system tunable that lets you set the number of compression threads on the Primary host or the number of decompression threads on the Secondary host between 1 and 64. The default value is 10. You can tune this setting dependent on your CPU usage.

Maximum size per message for resync or autosync

vol_dcm_replay_size

This tunable cannot be changed using the vxtune command.

The size of the DCM replay blocks. The default value is 256KB.

Maximum memory allocated for VVR nmcom pool

vol_max_nmpool_sz

The amount of buffer space available for requests coming in to the Secondary over the network. The default value is 64MB.

Maximum memory allocated for VVR readback pool

vol_max_rdback_sz

The amount of buffer space available for readbacks. The default value is 128MB.

vol_max_wrspool_sz

The write ship buffer space, which is the amount of buffer space that can be allocated on the logowner to receive writes sent by the non-logowner. The default value is 64MB.

Minimum Threshold for in-memory updates

vol_min_lowmem_sz

The minimum buffer space. VVR frees the write if the amount of buffer space available is below this threshold. The default value is about 520 kilobytes, twice the size of a maximum write. This value is auto-tunable. The value that you specify is used as an initial value and could change depending on the application write behavior.

vol_nm_hb_timeout

The heartbeat timeout value. The default value is 10 seconds.

Maximum memory allocated for VVR I/O pool

vol_rvio_maxpool_sz

The amount of buffer space that can be allocated within the operating system to handle incoming writes. The default value is 128MB.

Replication over NAT based Firewall

vol_vvr_use_nat

This tunable cannot be changed using the vxtune command.

This tunable parameter directs VVR to use the translated address from the received message so that VVR can communicate over a NAT-based firewall. Set this tunable to 1 only if there is a NAT-based firewall in the configuration.

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