FAST VP moves data once a day (during a relocation window). FAST Cache promotes data to SSD in near real-time, which allows it to respond to changing workloads much more rapidly. FAST Cache uses RAID1 (write penalty of 2) whereas FAST VP uses RAID5 (write penalty of 4). Thus FAST Cache is more efficient with a lot of random writes.
| FAST CACHE | FAST VP |
|---|---|
| Allows Flash drives to be used to extend the existing caching capacity of the whole storage system | Allows a single LUN to leverage the advantages of multiple drive types through the use of storage pools. |
| Granularity is 64 KB | Granularity is 1 GB |
Can I use both fast cache and fast VP together?
Of course you can use both at the same time: FAST Cache and FAST VP to yield high performance from the storage system. For example, you can use Flash drives to create FAST Cache, and use FAST VP for storage pools consisting of SAS and NL-SAS drives.
What is the difference between fast cache SSD and fast VP SSD?
FAST VP SSD are eMLC. SLC can sustain more IOPS per drive in comparison to eMLC. Roughly it like 5000 vs 3500 iops per drive, that is why FAST Cache SSD can be used for FAST VP drives, but FAST VP SSD can not be used for FAST Cache drives.
Can I use a flash drive for fast cache?
For example, you can use Flash drives to create FAST Cache, and use FAST VP for storage pools consisting of SAS and NL-SAS drives. Or even devide your Flash drives into two groups: one for FAST Cache usage, and second to use it in ‘extreme performance’ tier for your important storage pool.
What is fast VP and how does it work?
FAST VP accelerates the performance of a specific storage pool by automatically moving data within that pool to the appropriate drive technology, based on data access patterns. FAST VP is only applicable to hybrid pools within a Dell EMC Unity hybrid system.
What is fast cache?
FAST Cache is a high capacity secondary cache which logically sits below System Cache, and above the drives in the system. FAST Cache complements the System Cache by using Flash drives to service highly active data being requested from the drives.
WHAT IS FAST VP?
FAST VP accelerates the performance of a specific storage pool by automatically moving data within that pool to the appropriate drive technology, based on data access patterns. FAST VP is only applicable to hybrid pools within a Dell EMC Unity hybrid system.
How do I turn off write cache in unity?
DISABLE WRITE CACHE: Get the state of write cache: svc_cache --get (State 3 is enabled, state 7 is disabling/unknown, state 8 is disabled) Disable write cache: svc_cache --disable (The command only needs to be run on one SP to disable cache on both SPs) Confirm write cache is disabled: svc_cache --get.
What is the minimum recommended amount of Flash capacity in a Dell EMC Unity 480 hybrid pool?
5%The minimum recommended Flash capacity is at least 5% of the pool capacity.
What is fast cache in Vnx?
FAST VP. Allows Flash drives to be used to extend the existing caching capacity of the whole storage system. Allows a single LUN to leverage the advantages of multiple drive types through the use of storage pools. Granularity is 64 KB.
WHAT IS FAST VP in Vnx?
FAST VP differentiates each of these tiers by drive type, but it does not take rotational speed into consideration. EMC strongly encourages that you avoid mixing rotational speeds per drive type in a given pool. If multiple rotational-speed drives exist in the array, you should implement multiple pools as well.
What is SP in EMC storage?
Storage Processor in Service Mode The system or a user has placed the SP in Service Mode. An SP automatically enters Service Mode when it is unable to boot, due to a hardware or system software problem.
Can I delete unity cache?
Please use the button in Preferences -> GI Cache -> Clean Cache for clearing the cache directory, as this will ensure that the Editor releases all references to the files on disk before they are deleted.
What is unity cache?
When the Unity Package Manager downloads package contents and metadata, it stores them in a global cache. This makes re-using and sharing packages more efficient, and allows you to install and update stored packages even when offline.
What is dynamic pool?
Dynamic Pools is a Pool technology introduced for All Flash systems in Dell EMC Unity OE version 4.2 and later. Dynamic Pools replaces the previous Pool technology, now referred to as Traditional Pools, as the default Pool type for All Flash systems.
What is a consequence of using an 800 GB drive and five 400 GB drives in a Dell EMC unity XT dynamic pool?
What is a consequence of using an 800 GB drive and five 400 GB drives in a Dell EMC Unity XT dynamic pool? A Dell EMC Unity storage administrator needs to build a NAS server configuration to support failover between SPs and NAS resources.
What is Dell dynamic pools?
Dynamic pools implement advanced RAID technology. In dynamic pools, a RAID group is spread across drive extents in multiple drives. The required spare space is also spread across drive extents in multiple drives. When a drive fails, the extents on the failed drive are rebuilt to spare space extents within the pool.
How do I reduce the size of a unity project?
5 Proven Ways to Reduce Game Size in UnityCleaning Up and Removing Unnecessary Assets.Removing Unused Built-in Packages.Importing Images and Compressing Textures.ARMv7 vs ARM64 Architecture.Handling Unity Scenes and Runtime Instantiation.
How do I delete an asset bundle?
To remove asset bundle with all cached versions, you can use: Caching. ClearAllCachedVersions("YourCachedAssetBundleName"); this will removes all the cached versions of the given AssetBundle from the cache or use.
How do I install Unity cache server?
To install the Cache Server, download it from the Unity homepage. The links are frequently updated (Cache Server version changes), so the best is to go there and download the latest version for yourself. After downloading the zip file, unpack it wherever you like to store the cache (locally or on a remote server).
How does FAST cache work?
Data on LUNs that becomes busy is promoted to FAST cache. The promotions depends on the number of accesses (read and/or write) within a 64KB chunk of storage, and is not dependent on whether the data already exists in the DRAM cache. If you have FAST VP I/Os from extreme performance tier are not promoted to FAST Cache.
What is a fast cache miss?
When the first I/O is sent by the application , the FAST Cache policy engine looks for an entry in the FAST Cache memory map for the I/O’s data chunk. At this stage memory map is empty, the data is accessed from the HDD LUN. This is called FAST Cache miss. EMC claims there is minimal performance overhead when checking the memory map for every access to a FAST cache enabled LUN
What happens when a host I/O request is a write operation for a data chunk in Fast Cache?
If the host I/O request is a write operation for a data chunk in FAST Cache, and the write cache is not disabled for the LUN, the DRAM cache is updated with the new “write”, and an acknowledgment is sent back to the host. The host data is not written directly to the FAST Cache. When data needs to be moved out of the DRAM Cache, it is written to FAST Cache.
What does it mean when I/O is checked against the Fast Cache memory map?
Incoming I/O from the host application is checked against the FAST Cache memory map to determine whether the I/O is for a chunk t hat is already in FAST Cache. If the chunk is not in a FAST Cache, the I/O request follows the same path it would follow if the storage system does not have FAST Cache. However, if the data chunk is in the FAST Cache, the policy engine redirects the I/O request to the FAST Cache.
How many TB is fast cache?
FAST cache technology supplements the available storage-system cache (DRAM cache), adding up to 2 TB read/write FAST Cache. The nice trick is that FAST Cache addresses a hot spot anywhere in the array, both RAID group LUNs and storage pool LUNs. Hot Spot is simply a busy area on a LUN.
What is a DRAM cache?
Let’s start at the beginning: DRAM cache – is a storage-system component that improves performance by transparently storing data in very fast storage media (DRAM). It’s capacity is limited and very expensive.
How does FAST cache work?
Data on LUNs that becomes busy is promoted to FAST cache. The promotions depends on the number of accesses (read and/or write) within a 64KB chunk of storage, and is not dependent on whether the data already exists in the DRAM cache. If you have FAST VP I/Os from extreme performance tier are not promoted to FAST Cache.
What happens when a host I/O request is a write operation for a data chunk in Fast Cache?
If the host I/O request is a write operation for a data chunk in FAST Cache, and the write cache is not disabled for the LUN, the DRAM cache is updated with the new “write”, and an acknowledgment is sent back to the host. The host data is not written directly to the FAST Cache. When data needs to be moved out of the DRAM Cache, it is written to FAST Cache.
