What it is

Nimble Storage is an iSCSI solution they call “Converged Storage” which combines primary storage and data protection in a single system. The CS-Series is a 3U chassis with up to 32TB of primary storage space (SATA), a large MLC flash read cache, multi-core CPUs and four Quad-GbE I/O ports per controller. It uses a log-structured file system and a variable block architecture to provide 2X-4X in-line data compression and sequence data writes which improve performance, space efficiency and flash wear life.

What it does

Data compression technologies have been around for quite some time but their effectiveness at reducing storage capacity has typically been diminished by the fixed block sizes which traditional storage architectures have used. Nimble Storage’s Cache-Accelerated Sequential Layout (CASL) uses variable sized blocks which can more efficiently store compressed data, preserving the storage density gains made by this technology. Nimble uses a log-structured file system to enable faster random writes to flash and SATA drives (by sequentializing them). It also writes in full erase blocks to flash, reducing write amplification and improving endurance, enabling the use of MLC flash to keep costs down.

Nimble takes regular incremental snapshots of these compressed data and stores them on high capacity SATA disks. The system is designed to store 60-90 days of these space-efficient snapshots, creating very short recovery points and essentially eliminating the need for traditional backups. Nimble also includes replication capability to another Nimble box in a remote site. Leveraging its WAN-optimized data architecture, performance is comparable to that of off-site replication using a set of deduplication appliances.

Using an intelligent indexing scheme, CASL can keep the most active data on flash. This index has the ability to track data access patterns at a block-level granularity and can update flash within milliseconds in response to changes in application workload requirements, which helps maintain high random read performance. The sequencing of random writes mentioned earlier enables very good random write performance.

 

Why that matters

Backup takes lots of capacity, as mentioned earlier, 5-10x the capacity consumed by the data set on primary storage. For this reason, complex technologies have been developed and deployed to manage the storage and handling of all this data as it’s moved from high performance (primary storage) to high capacity (backup) storage platforms. Snapshot technologies do provide an effective method of storing and restoring data sets in very short time frames but, since snapshots are implemented on primary storage, their use is limited by the same cost structures. Disaster recovery adds another wrinkle to the equation, plus more cost and complexity as bandwidth and remote site infrastructure are factored into the mix.

Nimble’s software architecture (CASL) with its log-structured file system and variable block architecture enables it to support flash more effectively in conjunction with high capacity SATA drives to provide the performance and system I/O required by primary storage devices. This space efficiency results in an iSCSI system with significantly greater effective storage capacities and proportionately lower costs - 1/3 that of other iSCSI arrays is typical. In addition, this compression and snapshot technology enables the Nimble system to support backup and DR without adding more or separate capacity, as required by traditional storage systems. The result is a primary storage device that can also provide data protection and off-site DR, eliminating the cost and complexity associated with multiple storage devices and multiple storage applications.

Storage Switzerland’s Take

Nimble Storage is taking a different approach than other players in the storage industry. Instead of just letting you put ‘10 lbs (of primary data) into a 5 lb (backup storage) bag’ they’ve found a way to do backup and DR functions within the primary storage system itself. And their in-line compression and flash/SATA architecture produces a less costly primary storage alternative to traditional iSCSI modular arrays. Finally, Nimble simplifies the entire storage-protection infrastructure and makes it appealing to IT organizations that aren’t heavy with storage experts to manage the whole primary/backup/DR storage complex - or just have other things to do.