Create a Ram Disk in Exalytics (LINUX)

So you have all your data in memory, how can you make it even faster. You can create what you call a RAM Disk, this is when you have allocated part of the memory to be used as a file system, then configure BI to use the ram filesystem for caching.
1. Check the amount you have free ram you have left on your machine, by using the command free –g, you can see we have 1tb ram.

             total       used       free     shared    buffers     cached
Mem:          1009       1006          2          0          2        174
-/+ buffers/cache:        830        179
Swap:           96          0         96

2. Create a folder to use as a mount point for your RAM disk.
mkdir /mnt/ramdisk
3. Add the following into the /etc/fstab file in the size add the size you want, we are using 1g:
tmpfs /mnt/ramdisk tmpfs nodev,nosuid,noexec,nodiratime,size=1024M 0 0
4. Enter the following to mount it : mount /mnt/ramdisk
5. To check all mounted df-k

Filesystem           1K-blocks      Used Available Use% Mounted on
                     468665392  82965052 361509364  19% /
/ dev/sdb1            1727340468 1146178432 493418224  70% /u01
tmpfs                  1048576    494436    554140  48% /mnt/ramdisk
dev/sda1               101086     25854     70013  27% /boot
tmpfs                529478108         0 529478108   0% /dev/shm

6. On the BI Server edit the
7. Update the DATA_STORAGE_PATHS as below, don’t update anything else.
ENABLE = YES; # This Configuration setting is managed by Oracle Enterprise Manager Fusion Middleware Control
# A comma separated list of pair(s).
# These are relative to the process instance directory.
# e.g. DATA_STORAGE_PATHS = “nQSCache” 500 MB;
# resolves to
# $(ORACLE_INSTANCE)/bifoundation/OracleBIServerComponent/<instance_name>/nQSCache
#DATA_STORAGE_PATHS = “cache” 500 MB;
DATA_STORAGE_PATHS = “/mnt/ramdisk” 500 MB;
8. Lets set up OBIEE to use ramdisk for the presentation cache by doing the following in the OBIEE 11g EM console:
FMW Control > Business Intelligence > CoreApplication > Capacity Management tab
9. Then click the Performance tab, tick ‘cache enabled’ under ‘Enable BI Server Cache’
10. Restart the BI Services.
Next time I will show you how to automatically clear the cache.