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2. - Chapter 5 # Using and Managing System Files For information about how to manage system files, see the following sections: Using Data Caches in Shared File Systems Changing the Location of the Scoreboard Bitmap Managing Differences Between Files That Are Not Shared Using the Naming Services ## Using Data Caches in Shared File Systems If the impact on performance is acceptable, do not use data and attribute caches when writing data to shared file systems. If it is necessary to use data and attribute caches to improve performance, ensure that your applications minimize the risk of using inconsistent data. Consider using the `O_SYNC` or `O_DSYNC` mount options on some files. For information about these options, see the `fcntl`(3head) man page. Data and attribute caching is disabled by the `noac` mount option. The following procedure describes how to enable or disable the `noac` mount option. ### To Enable or Disable Data and Attribute Caching Log in to the vice-master node as superuser. Open the `/etc/vfstab` file in a text editor. If data and attribute caching is disabled, the file should contain the `noac` option, as follows:
         master-cgtp:/SUNWcgha/local/export/data -       \
         /SUNWcgha/remote  nfs     -       no    rw,hard,fg,intr,noac

         master-cgtp:/SUNWcgha/local/export/services/ha_v21/opt  \
         -    /SUNWcgha/services   nfs     -   no   rw,hard,fg,intr,noac

         master-cgtp:/SUNWcgha/local/export/services     -     \
         /SUNWcgha/swdb  nfs    -       no     rw,hard,fg,intr,noac
   - If data and attribute caching is enabled, the file should not contain the `noac` option, as follows:
         master-cgtp:/SUNWcgha/local/export/data -       \
         /SUNWcgha/remote  nfs     -       no    rw,hard,fg,intr

         master-cgtp:/SUNWcgha/local/export/services/ha_v21/opt  \
         -    /SUNWcgha/services   nfs     -   no   rw,hard,fg,intr

         master-cgtp:/SUNWcgha/local/export/services     -     \
         /SUNWcgha/swdb  nfs    -       no     rw,hard,fg,intr
5. Remove or add the `noac` option, as required. To enable data and attribute caching, remove `noac` from the lists of options. To disable data and attribute caching, add `noac` to the lists of options. Save and close the file. Reboot the node:
       # uadmin 1 1
5. Trigger a switchover, as described in To Trigger a Switchover With `nhcmmstat`. Repeat Step 1 through Step 5 on the new vice-master node. Log in to each of the diskless peer nodes or dataless peer nodes and repeat Step 2 through Step 5. ## Changing the Location of the Scoreboard Bitmap When data is written to the master node, a write is made to the replicated partition on the disk and to the corresponding scoreboard bitmap. The scoreboard bitmap can be configured in two ways: The scoreboard bitmap can be stored on a replicated partition and updated every time that the corresponding data partition is updated. The scoreboard bitmap can be stored in memory and updated every time that the corresponding data partition is updated. The scoreboard bitmap is written to a replicated partition only when the node is shut down gracefully. For information about the advantages and disadvantages of storing the scoreboard bitmap in memory, see "IP Mirroring" in the Netra High Availability Suite Foundation Services 2.1 6/03 Overview. For information about how to reconfigure the scoreboard bitmap, see the following procedure. ### To Change the Location of the Scoreboard Bitmap Log in to the vice-master node as superuser. Open the `/usr/kernel/drv/rdc.conf` file in a text editor. If the scoreboard bitmap is stored on a replicated partition, the value of the `rdc_bitmap_mode` parameter is 1. If the scoreboard bitmap is stored in memory, the value of the `rdc_bitmap_mode` parameter is 2. Change the value of the `rdc_bitmap_mode` parameter: To store the scoreboard bitmap on a replicated partition, set the value of the `rdc_bitmap_mode` parameter to 1. To store the scoreboard bitmap in memory, set the value of the `rdc_bitmap_mode` parameter to 2. Save and close the file. Reboot the node:
       # uadmin 1 1
Trigger a switchover, as described in To Trigger a Switchover With `nhcmmstat`. Repeat Step 1 to Step 5 on the new vice-master node. Verify that the master node and vice-master node are synchronized, as described in To Verify That the Master Node and Vice-Master Node Are Synchronized.
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