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Changing the cache size for a virtual machine
When you set the cache size for a virtual machine, you reserve a portion of the flash device on the ESXi host for use as cache by applications running on the virtual machine. Flash Accel performance statistics will tell you whether you have too much or too little cache allocated for a VM.
Before you begin 
The virtual machine must be configured with memory sized appropriately for the cache size, approximately 0.6 GB of RAM for every 100 GB of cache. So if you are planning to provide 250 GB of cache for the virtual machine, you should configure 1.5 GB of RAM (in addition to whatever RAM is required to run the virtual machine and applications).
You must disable caching on the virtual machine before changing the cache size.
Information in the cache is erased for all disks on the virtual machine when you change the cache size. The cache will take some time to be rewarmed after the cache size is changed.
Steps 
1.
From the home page of the Flash Accel Management Console, click the wrench icon for the virtual machine on which you want to change the cache size and select Cache State > Disable.
You can perform all of the tasks in this procedure from the VM directory or the VM details page as well as the home page.
2.
The Cache Space dialog box opens.
3.
4.
The Cache Space dialog box opens.
5.
To enter the cache size manually, click the Enter Manually check box, then enter the cache size in the Enter Cache Space Size field.
Depending on the cache size you specified, formatting the flash device can take five minutes or more.
The Cache Size field for the virtual machine is set to the specified value.
6.
The Cache State field for the virtual machine is set to Enabled.
Result 
Caching resumes and the cache is rewarmed.
After you finish 
If you changed the cache size by a large amount, you may need to resize the RAM configured on the virtual machine. Make sure to maintain the recommended ratio of approximately 0.6 GB of RAM for every 100 GB of cache.
Parent Topic: Managing Flash Accel caching systems


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