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30 Cards in this Set
- Front
- Back
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What are the two components of a block-based storage system?
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Controller (FE ports, Cache and BE ports) and Storage |
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Read hit
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Data is found in cache following a read request
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Read miss
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Data is not found in cache following a read request |
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Prefetch |
A read-ahead algorithm that calls sequential data into cache to improve read time |
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Write hit
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Following a write request data is dumped in cache and an acknowledgment sent back to the compute system. Data is written into backend storage later on. (Also known as write-back cache) |
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Write miss
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Following a write request data is immediately written to backend storage, no time is spent waiting on cache. (Also known as write-through cache)
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LRU
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Least recently used. Is an algorithm used to free up cache that has not been accessed recently |
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MRU |
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Idle Flushing
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Dumping cache into storage, continuously at a modest rate |
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High Watermark Flushing (HWM)
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When cache utilization hits a threshold causing it to speed up the flushing process |
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Dirty Page
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Data written into cache but not yet written to backend storage
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Forced Flushing
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When cache utilization reaches 100% the system will flush the cache on priority by allocating more resources |
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Cache Mirroring
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Each write to cache is held in two different memory locations on two independent memory locations |
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Cache Vaulting
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When power failure occurs the controller and a few discs remain powered on by battery until all Write Pending cells are flushed into storage |
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Storage Provisioning
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The process of assigning storage resources to compute system based on capacity, availability, and performance requirements |
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LUN
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Logical Unit Number. A partitioned chunk of storage from the RAID set |
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MetaLUN
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A method to expand LUNs that require additional capacity or performance |
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Concatenated metaLUN
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Adding additional capacity to the base LUN. Once the base LUN is full new data will be written to the extended capacity. LUNs can be variable size and RAID levels |
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Striped metaLUN
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Striped expansion involves restriping the base LUNs data across the newly added LUN. This can take time to configure but will improve performance due to increased number of striped LUNs |
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LUN Masking
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A process that provides data access control by defining which LUNs a compute system can access |
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Storage Tiering
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A technique of establishing a hierarchy of storage types (tiers) and identifying the candidate data to relocate to the appropriate storage type to meet service level requirements at a minimal cost |
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Sub-LUN Tiering
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A LUN is broken down into smaller parts that are separately tiered based on performance |
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Cache Tiering
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SSDs are used to create a large capacity secondary chance to enable performance tiering between DRAM and SSDs
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Server Flash-caching
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a PCI Express-based flash card is installed directly on the compute system which reduces latency and accelerates throughput
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XtremIO
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-All Flash -Block-based -High I/O performance -Node based architecture for scale-out -Operating system: XIOS |
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VNX-F
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Block-based SSD only storage
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FAST VP
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-Moves data that is not frequently used to lower tiers and vice versa |
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XtremSF
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-PCIe flash card deployed on the compute system -Used in conjunction with XtremCache |
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XtremCache |
-Protects data with write-through cache to the networked storage |
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