D-Link DSN-6210 User Manual - Page 132
Populating the Cache, Read/Write Cache Cases, Read Data with Cache Miss
View all D-Link DSN-6210 manuals
Add to My Manuals
Save this manual to your list of manuals |
Page 132 highlights
D-Link Document - User Manual Populating the Cache The actions that read data from the HDD and write to the SSD are called populating the cache. It is a background operation that typically immediately follows a host read or write operation. The constraint is that two parameters are used to determine when to start a cache-populate operation: 1. Populate-on-read threshold: The value is great than zero. If it is zero, no action is performed for read cache. 2. Populate-on-write threshold: It's the same action as read. According to these values, each cache block has associated to its read and write counts. When a host requests the read data located on the cache block, its read count is increment. If a cache hit does not occur, and the read count is greater than or equal to the populate-on-read threshold, then a cache-populate operation is performed with the host read concurrently. If a cache hit occurs, a populate operation is not performed. If the read count is smaller than the threshold, the count continues and a populate operation is not performed neither. For write cases, it's the same scenario as read. We provide the figures to describe the following in more detail. Read/Write Cache Cases Read Data with Cache Miss The following figure shows the steps of the controller which handles a host read request when some of the data is not in the SSD cache. Copyright@2014 D-Link System, Inc. All Rights Reserved. 132