CASL Hybrid Storage Architecture
Nimble Storage solutions are built on the patented Cache Accelerated Sequential Layout (CASL™) architecture. CASL differs from the traditional bolt-on approach of using flash as a tier. Instead, CASL is designed from the ground up as a hybrid solution to leverage the lightning-fast random read performance of flash and the cost-effective capacity of hard disk drives. CASL also incorporates innovative efficiency features, such as inline variable-block compression, cloning, and integrated snapshots, to store and serve more data in less space.
Key Innovations from CASL
- Dynamic Flash-Based Read Caching
CASL caches "hot" active data into a flash-based SSD in real time—without need to set any complex policies. This way it can instantly respond to read requests—as much as 10X faster than traditional bolt-on or tiered approach to flash. - Write-Optimized Data Layout:
CASL collects or coalesces random writes to the array, compresses and writes them sequentially to disks. This results in write operations that are as much as 100x faster than traditional disk-based storage. - Inline Compression
CASL compresses data as it is written to the array with no performance impact. It takes advantage of efficient variable block compression and multicore processors. A recent measurement of our install base shows average compression rates from 30 to 75 percent for a variety of workloads. - Scale-to-Fit Flexibility
CASL allows for the non-disruptive and independent scaling of performance and capacity. This is accomplished by either upgrading the storage controller (compute) for higher throughput, moving to larger flash SSD (cache) to accommodate more active data, or by adding storage shelves to boost capacity. This flexible scaling eliminates the need for disruptive forklift upgrades. - Snapshots and Integrated Data Protection
CASL can take thousands of point-in-time instant snapshots of volumes by creating a copy of the volumes' indices. Any updates to existing data or new data written to a volume are redirected to free space (optimized by CASL's unique data layout). This means there is no performance impact of snapshots and snapshots take little incremental space as only changes are maintained. This also simplifies restoring snapshots as no data needs to be copied. - Efficient Replication
Nimble Storage efficiently replicates data to another array by transferring compressed, block-level changes only. These remote copies can be made active if the primary array becomes unavailable. This makes deploying disaster data recovery easy and affordable – especially over a WAN to a remote array where bandwidth is limited. - Zero-Copy Clones
Nimble Storage arrays can create snapshot-based read/writable clones of existing volumes instantly. These clones benefit from the fast read and write performance, making them ideal for demanding applications such as VDI or test/development.
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"[Nimble Storage's] compression has been remarkable—and especially on VDIs, where today we are seeing compression of between 60 and 80 percent. Now, we have literally four times the space and our expansion options are seemingly limitless."
Tony Banken, Network Administrator at Central Minnesota Jobs & Training Services