Nimble Storage is a convergence device of a different sort. Instead of focusing on unifying primary storage protocols, they are unifying primary storage, backups and disaster recovery into a single device. The goal is essentially to allow storage managers to buy a single storage device that handles the entire stack.
Nimble accomplishes this by creating a new storage architecture called CASL (Cache Accelerated Sequential Layout). The primary ingredient for CASL is variable inline compression. This brings an immediate 50% to 75% savings in capacity requirements and its variable nature allows compression to maintain good performance across a wide range of I/O types. Essentially both sequential and random I/O workloads perform equally well even though their data is compressed.
The next ingredient is a combination of flash storage and capacity hard drive storage. The flash is only used as a caching area, not a storage tier which actually simplifies the product considerably. The unit has mirrored NVRAM front end that allows for efficient write layouts to make sure that data is placed on storage in its most efficient manner, meaning a full erase block in flash and a complete RAID stripe on disk. All the data is written to disk but thanks to the NVRAM random I/O data sets can be immediately promoted to the flash cache. This allows for the unit to provide immediate performance improvements on active data sets. In comparison, auto-tiering solutions that seem to be popular with the legacy storage vendors can make applications wait for hours before they are promoted to the faster tiers.
Another important advantage of using the flash tier as cache is that there is no storage processing time and bandwidth wasted in the swap out of data from the solid state storage area. In the Nimble world view there is no solid state tier, its a cache and the data is already on disk.
The next step is an intelligent use of snapshot data which again benefits from the compression intelligence to be able to allow long term retention of snapshotted data. CASL is designed as a few of the more modern storage systems are to suffer no performance impact from snapshot retention. The challenge is providing the capacity requirements to retain that data. Compression extends the snapshot reach significantly. Nimble claims up to a 90 day snapshot retention with their systems, which certainly fulfills the medium term backup requirement for most companies. Longer term retention can be handled by running a monthly full backup or again because of compression, just don’t delete the data and let it be stored on the Nimble system for years.
The final ingredient, and maybe most important if you are going to eliminate or at least decrease your backup frequency, is to get data to a second unit, preferably off-site. The snapshot technology is leveraged to provide WAN efficient replication to move only the changed blocks to the disaster recovery unit. The disaster recovery unit can have a separate snapshot schedule to prevent a replication of corrupt data from poisoning the DR unit.
Storage Swiss Take
Nimble it seems to me accomplishes its convergence goal. This is a single platform that leverages SSD in a cost effective way such that the mid-sized market can afford the high speed technology while at the same time leveraging snapshots and replication to eliminate or dramatically reduce an organizations dependance on backup and DR products. The combination of using MLC based flash, compression, and then, because it is cache, not having to run a RAID protection scheme on it brings a dramatic reduction to the cost of deploying solid state storage. In short for the mid-range market Nimble should be able to improve performance, reduce storage capacity needs, reduce storage administration times and reduce backup costs.
Nimble Storage is a client of Storage Switzerland