D-Link DSN-626 User Manual - Page 131

Solution, Methodology, system is 2.4TB.

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D-Link Document - User Manual needs to be as high as possible. In recent years, the capacity of HDDs has increased but their random input/output (I/O) has not increased at the same rate. For some applications such as enterprise web with database, cloud and virtualization which require both high capacity and performance, HDDs have the superiority in capacity but lower speed. It means the pure HDD storage is not enough for those applications. Using the superiority of SSDs, offer exceptionally high speed, SSD caching technology provides the best way to fulfill cost-effectively the performance and capacity requirements of their enterprise applications. Integrated HDDs and SSDs into the storage combine the benefits of both. SSD cache feature enables the system to use SSDs as extended cache, thus increasing the performance of random I/O applications such as databases, file servers, and web servers, etc. Generally, the SSD caching is useful for the following features: 1. Due to the HDD IOPS, read performance cause the bottleneck. 2. In working space, read I/O is much more than write. 3. The best performance is in the case, the working data size is repeatedly accessed and smaller than the size of SSD cache capacity. Solution SSD caching is the secondary cache used to enable better performance. One and more SSDs could be assigned to a single virtual disk to be its SSD caching space. Please note that the cache volume is not available for regular data storage. Currently, the maximum SSD cache size allowed in a system is 2.4TB. Methodology When the read or write I/O performs, this feature copies the data from HDD into SSD. At the next time, any subsequent I/O read of the same logical block addresses can be read directly from SSD. It increases the overall performance with a much lower response time. If the SSDs fail unfortunately, you won't worry about the data loss because the data caching in the SSD is a copy of the original which is residing on HDD. SSD caching is divided into group of sectors of equal sizes. Each group is called a cache block; each block is divided into sub-blocks. The I/O type configured for a virtual disk would affect size of the cache block and size of sub-blocks. Copyright@2014 D-Link System, Inc. All Rights Reserved. 131

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D-Link Document – User Manual
needs to be as high as possible. In recent years, the capacity of HDDs has increased but their
random input/output (I/O) has not increased at the same rate. For some applications such as
enterprise web with database, cloud and virtualization which require both high capacity and
performance, HDDs have the superiority in capacity but lower speed. It means the pure HDD
storage is not enough for those applications.
Using the superiority of SSDs, offer exceptionally high speed, SSD caching technology provides the
best way to fulfill cost-effectively the performance and capacity requirements of their enterprise
applications. Integrated HDDs and SSDs into the storage combine the benefits of both. SSD cache
feature enables the system to use SSDs as extended cache, thus increasing the performance of
random I/O applications such as databases, file servers, and web servers, etc.
Generally, the SSD caching is useful for the following features:
1.
Due to the HDD IOPS, read performance cause the bottleneck.
2.
In working space, read I/O is much more than write.
3.
The best performance is in the case, the working data size is repeatedly accessed and
smaller than the size of SSD cache capacity.
Solution
SSD caching is the secondary cache used to enable better performance. One and more SSDs could
be assigned to a single virtual disk to be its SSD caching space. Please note that the cache volume
is not available for regular data storage. Currently, the maximum SSD cache size allowed in a
system is 2.4TB.
Methodology
When the read or write I/O performs, this feature copies the data from HDD into SSD. At the next
time, any subsequent I/O read of the same logical block addresses can be read directly from SSD. It
increases the overall performance with a much lower response time. If the SSDs fail unfortunately,
you won’t worry about the data loss because the data caching in the SSD is a copy of the original
which is residing on HDD.
SSD caching is divided into group of sectors of equal sizes. Each group is called a cache block; each
block is divided into sub-blocks. The I/O type configured for a virtual disk would affect size of the
cache block and size of sub-blocks.
131
Copyright@2014 D-Link System, Inc. All Rights Reserved.