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Can you compare caching at the network level with flash caching in the server? What are the pros and cons of each?
There tends to be three types of flash caching implementation methods available: storage-system caching, network-level caching and server-based caching. Storage-system and network-based caching are similar in that they provide the performance boost of flash to all the physical or virtual servers in the environment, regardless of which host they are running. Server-side caching typically provides the performance boost to VMs running on a specific physical server -- although products are emerging that allow server-side flash resources to be shared.
Beyond the number of servers impacted, storage system and network caching do not have the concerns that server-side caching does as it relates to virtual machine migration as discussed in a previous Expert Answer. It generally is also safer to perform write caching on these systems. There is less risk of data loss compared with server-based caching.
Network-based caching generally refers to an appliance that can provide caching to any servers on the network, as opposed to storage-based caching, which is integrated into a specific storage system. This type of flash caching is generally tied to a single system and a single vendor's technology. Network-based caching can provide a performance boost across a wide range of storage systems. Also, network-based caching can typically integrate easily with existing systems because they plug into the network and sit between storage and servers.
Flash hypervisors, caching engines similar, but not the same
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