G00215858
Identify the Right Gateway Product for Storage
in the External Cloud
Published: 25 August 2011
Analyst(s): Pushan Rinnen, Gene Ruth, Stanley Zaffos
This report analyzes the emerging external cloud storage gateway market
and profiles some key vendors and products for Gartner's user clients. As
external cloud storage offerings become increasingly available, it is
important for user clients to know what gateway choices are available when
they want to leverage cloud storage to augment or replace their
on-premises storage.
Key Findings
■ Gateways for external cloud storage augment or replace local storage with cloud storage and
play an important role in the overall success of external cloud storage services.
■ These gateways are not yet ready for enterprise-scale data center deployment but can address
branch office storage requirements in many cases.
■ The majority of the data that the gateways push to the external cloud today are
latency-insensitive workloads, such as backup, disaster recovery, and inactive file data.
■ Many vendors in this space are startups with very limited installed bases.
Recommendations
■ Make cloud storage gateways part of any plan to access cloud storage, but proceed cautiously
due to the nascent nature of the gateway product category.
■ Plan to use multiple public cloud providers to minimize dependence on a single cloud storage
service provider.
■ Create mitigation plans to access cloud data in case the gateway vendors exit the market. ■ Choose gateways that compare well against conventional SAN or NAS disk arrays and map
What You Need to Know
An external cloud is an IT capability that is offered as a service to a business and that is not hosted by the business's IT organization. An external cloud can be public or private, but must be
implemented by a third-party service provider. With the emergence of external public cloud storage services offerings such as Amazon S3 has come a new crop of independent cloud gateway vendors and products to help users leverage public cloud storage. At the same time, some cloud gateways have been developed to augment external private cloud storage services. These gateways are on-premises appliances that offer an easier-to-manage and/or more efficient way to migrate data to an external cloud.
Gateway architectures vary by vendor and are often tailored to address specific workload types. Some use embedded internal storage as a local cache to boost performance; others focus on local storage tiering with cloud storage as an extended tier. Some are dedicated for backup data only; some are designed to archive older files to an external cloud; and others are more versatile with different use cases. Some focus on supporting multiple public cloud storage platforms, while others focus more on supporting external or internal private cloud storage services. The brand-new
products designed from the ground up tend to have more comprehensive features for the cloud, whereas repositioned products are still weak in their cloud support capabilities. This research doesn't include gateways available only through a specific service offering, as users of that particular services offering would not have the option of choosing a different gateway.
Analysis
Market and Technology Definitions and Segmentation
Gartner defines an external cloud as an IT capability that is offered as a service to a business and that is not hosted by the business's own IT organization. An external cloud can be public or private, but must be implemented by a third-party service provider. All public clouds are external, but a private cloud can be internal or external. This research focuses on gateways that bridge to external cloud storage.
Gartner defines public cloud storage as a storage utility offering owned by a public cloud service provider that uses the pay-per-use model and software-agnostic, reservationless provisioning. Examples include Amazon S3, Microsoft Windows Azure Storage and Nirvanix. External private cloud storage is defined as a storage utility offering owned by an external private cloud service provider whose storage services are subscribed to by a select group of organizations — not just any consumer. Examples include some regional telecom providers and managed service providers. The external cloud storage gateway market includes a new set of products that function as on-premises gateways (hardware or software appliances) to cloud storage. They connect to external cloud storage via Internet APIs or protocols such as REST or HTTP. They support local servers or clients via standard storage access protocols such as Internet Small Computer System Interface (iSCSI), Network File System (NFS) and Common Internet File System (CIFS). Architecturally, they
■ Cache devices — The gateway provides advanced caching algorithms to mask performance
limitations associated with cloud storage. Examples of this type of gateway include Nasuni, Riverbed Whitewater, and TwinStrata. All of these focus on leveraging public cloud storage.
■ Tiered devices — The gateway provides on-premises storage tiers such as solid-state drives
(SSDs) and disk drives, as well as cloud tiers that reside at cloud storage service providers. Two distinct product types exist within this category. One has integrated local storage tiers, such as StorSimple, which was designed from the ground up for leveraging public cloud storage. The other is repositioned file virtualization devices that can migrate or tier data among other on-premises storage arrays and the cloud. Examples include EMC's Cloud Tiering Appliance and F5 Networks' ARX Cloud Extender, both of which do not store user data on the appliances.
■ Copy/synchronization devices — The gateway provides remote replication and synchronization
services among the same devices deployed at different sites (both user premises and external private cloud providers' sites), similar to those offered by conventional storage arrays for an internal cloud. Examples include CTERA Networks and Panzura.
Gartner also calls those gateways with embedded local primary storage "hybrid storage
appliances," which are designed to serve limited local primary storage for the most active data, while pushing relatively inactive data to the public cloud via an embedded gateway that connects to the cloud storage seamlessly. To the users and hosts, it behaves as a normal storage system. The term "hybrid" is used to describe the attribute of combining local storage and cloud storage. From a data flow perspective, it is a storage target or an in-band appliance that intercepts all input/outputs (I/Os) to and from a virtual volume or file system. From a storage system perspective, it uses
sophisticated cache management algorithms to minimize data flows to and from the public cloud by satisfying as many I/Os as possible from local storage. Data is often compressed or deduplicated in the appliance to increase its effective cache capacity, and when data is actually transferred to or from the cloud; WAN-optimized controller (WOC) techniques are often used to reduce the impact of link latency on performance. Examples of hybrid storage appliances include CTERA, Nasuni,
Panzura, StorSimple and TwinStrata.
Introduction
External cloud storage gateways are a nascent phenomenon, because external cloud storage services are still in the early stage of development. A viable offering of external cloud gateway appliances didn't really emerge until 2010. Nevertheless, as long as external cloud storage remains a viable alternative to customers' internal storage deployment, we expect those gateway products will continue to have their value, such as boosting performance, increasing storage efficiency and simplifying cloud storage management. Gartner expects the gateway market to expand, enable and accelerate the acceptance of external cloud storage.
Market Analysis
External cloud storage gateways are peripherals to external cloud storage services. The gateways' future, therefore, is very much dependent on the success of overall external cloud storage services, as well as on reliable products from solid vendors. For enterprise customers, gateways are an
essential component of cloud storage solution, as they can help overcome some key issues associated with external cloud storage such as performance.
While public cloud storage offers potential cost and agility advantages, which fit the need for consumers and ad hoc projects such as test and development, they may frequently suffer from lower security, weaker SLAs, looser integration with on-site applications, and lower reliability. The lack of transparency in storage architecture and data protection schemes deployed by some major public cloud storage service providers does not help generate confidence among business
customers who want to develop tighter and deeper long-term relationships.
In contrast, external private clouds tend to have higher-cost storage infrastructure because they often acquire commercial storage systems instead of building their own infrastructure. However, their strengths may include stronger SLAs, deeper integration with on-site applications and higher levels of reliability and security and can often justify the higher cost. Because they deploy
commercial products, whose features and functions are more readily available, business customers with internal storage know-how may feel more comfortable about leveraging external cloud storage to gain the benefits of agility, such as global data accessibility, without internal private
infrastructure, outsourced management of backup and disaster recovery, and potentially lower total cost of ownership.
Overall, all hybrid storage appliances — those gateways with internal storage for local cache or primary storage — can offer predictable performance and operations for local users and, in some cases, can replace on-premises disk arrays. However, some gateways are designed to alleviate some of the pain points associated with using public cloud storage specifically. For example, support of simultaneous access to more than one public cloud, cloud snapshots and clones, and encryption of data in flight and at rest will increase the data availability, recoverability and security in the public cloud. These gateways are typically offered by startups. Other gateways are created by vendors that want to use the gateway as a facilitator to increase their storage platform sales to the external private cloud service providers. For example, EMC's and F5's appliances have been around for many years to provide user-transparent file migration among different local tiers of storage and have recently been retrofitted with cloud storage access protocols such as REST. They lack some cloud-focused features such as deduplication, WAN optimization and cloud snapshots and cloning. They may or may not be able to preserve the native deduplication on the local storage systems when they move data to the cloud.
Key Vendors and Products in the Market
Although we segment external gateway devices into three architectural categories based on some key attributes, every single one is designed somewhat differently. Those designed from the ground up for public cloud storage are typically from startups, including Nasuni, StorSimple and TwinStrata; whereas startups CTERA and Panzura focus more on providing infrastructure technologies for hybrid cloud and private cloud service providers. Established vendors such as EMC and Hitachi aim to protect their own turf by offering gateways to augment their respective cloud infrastructure storage platforms — Atmos and Hitachi Content Platform (HCP). Riverbed is leveraging its WAN optimization know-how to enter a new market. Table 1 groups the vendors and products by the three categories and lists some of the key feature functions as a reference for users who plan to
Table 1. External Cloud Gateways Comparison, 2011 Compa-ny/ Product Archi-tecture Cloud Services APIs Client-Side Proto-cols OS/Apps Supported Encryption Policy to the Cloud Dedup-lica-tion/ Compres-sion WAN Opti-mi-zation Snapshots/ Cloning in the Cloud Gateway Storage Details CTERA/ Cloud At-tached Storage and Cloud Portal Copy/
synch Hybridcloud stor-age that supports CTERA Portal, which can further con-nect to public cloud stor-age CIFS, NFS, iSCSI Microsoft Ex-change, SQL, Active Direc-tory and SharePoint AES-256 en-cryption, SHA-1 fin-gerprint File meta-data-based policy Block-level de-dupe, which can be applied across multiple appliances/ sites; compres-sion ratio be-tween 2x and 20x Leverage de-dupe; only change delta sent to the cloud Snapshots can be stor-ed both lo-cally and in the cloud; portal stor-age nodes can be cloned for HA 2-8 SATA drives, de-livering thin- provi-sion-ed storage for data and metadata
Panzura Copy/
synch Hybridcloud stor-age (REST or SOAP and Rsync over SSH, NFS), which can further con-nect to public cloud stor-age etc. NFS/ CIFS, iSCSI or MS SQL API, VTL/ NDMP to inter-face tape or disk backup soft-ware MS Share-Point and SQL; Syman-tec NetBack-up or backNetBack-up scripts Yes (RSA-2048 and AES-256 Replication policies be-tween no-des or be-tween a node and one or more pub-lic cloud provider; can go down to di- rectory-lev-el granular-ity Live, local or global block dedupe dic-tionary — part of metadata; compres-sion ratio: up to 95%
Only the data change delta is exchanged across con-trollers; where possi-ble, multiple TCP ses-sions are used in par-allel to re-duce the la-tency effects. Policy-based snap-shots at di-rectory lev-el; cloning is at directory or file level; metadata snapshots are sent to all control-lers for syn- chroniza-tion; data snapshots are mounta-ble from multiple lo-cations. HDDs (8TB and 24TB) or SSDs or both; RAID 10
Hitachi/ HDI Cache Private cloud based on Hitachi Content Platform CIFS, NFS CIFS/NFS files No (HCP of-fers encryp-tion for data at rest)
All copied to cloud
No (HCP in the cloud has sin-gle instance store and com-pression)
Yes (via part-nership with Silver Peak) No local or SAN attach-ed; store cloud repli-cated files and cloud archived stubs Nasuni/
Filer Cache Publiccloud stor-age, such as Amazon S3, EMC Atmos, Mi-crosoft Windows Azure Stor-age, Nirva-nix, Rack-space, etc. CIFS and NFS
Any that work with CIFS/ NFS On-premises encryption with OpenPGP/ AES-256 Can set cache size, schedule the fre-quency and reten-tion peri-ods of snapshots (unlimited), volume quotas Subfile based dedupe; aver-age 30% (up to 90%) space savings Only change delta at sub-file level be-tween snap-shot intervals is sent to the cloud after being com-pressed File system snapshot hourly by default and sent to the cloud; cus-tomer can restore to any point in the life of a file, directo-ry or file system. Software in-stalled on a virtual serv-er, emulat-ing Win-dows file server; ca-ches both data and metadata with local storage at-tached to the virtual server; can also cache snapshots. Riverbed/ Whitewa-ter Cache Public cloud stor-age such as Amazon S3 and EMC At-mos, etc. CIFS, NFS Backup target for NetBack-up, Backup Exec, TSM, NetWorker, Vizioncore and CA ARC-serve User existing solution Use third-party back-up soft-ware policy Subblock gran-ular (to 16 bytes) dedupe; can be applied across vol-umes; paten-ted algorithm used by Steel-head; com-pression ratio: 20-30x Transaction-ally aware, parallel cloud object store: reduce laten-cy for REST API No — not used for pri-mary data Unified RAM and HDD cache (7TB or 11TB raw); RAID 6
TwinStra-ta Cache Public cloud stor-age, such as Amazon S3, as well as cloud storage based on EMC At-mosScality Ring, Me-zeoCloud, etc.
iSCSI All apps — collaboration (Exchange, VMware), backup/DR (Backup Exec, CA ARCserve) Yes (AES-256) Can set policy on local cache and cloud provider parameters No dedupe; Gzip compati-ble No In-cloud snapshots triggered by users Cloud vol-ume is par-tially cach-ed locally; cloud repli-ca is 100% cached lo-cally via async repli-cation. Dy-namic and adaptive caching EMC/ Cloud Tiering Appli-ance Tiered Public or private cloud stor-age based on EMC At-mos CIFS,
NFS CIFS/NFSfiles No Schedula-ble migra-tion policy
Compressed files stay com-pressed in dif-ferent tiers No No, cannot send local snapshots to the cloud Appli-ances do not store or cache data, but store meta-data; can run on VMs F5/ARX Cloud Extender Tiered Public or private cloud stor-age based on EMC At-mos, Ne-tApp Stora-geGRID
CIFS CIFS files Yes (AES-256)
Schedula-ble migra-tion policy
No (deduped files will be hy-drated before sending to the cloud) No No, cannot send local snapshots to the cloud Software runs on a Windows file server, with local storage caching metadata for files sent to the cloud; sup-ports virtual server HA or physical server clus-tering
StorSim-ple Tiered Public cloud stor-age such as Amazon S3 and Windows Azure and cloud stor-age based on EMC At-mos iSCSI VMware 3.5/4.0/4.1, Hyper-V, Win-dows Server 2008 R2 User existing encryption solution or StorSimple's encryption with AES-256 Automati-cally moves data across SSD, SAS and cloud tiers based on access frequency and age; transaction log vols. are treated with higher priority. Users can also pro-vide explic-it priorexplic-ities. Subblock-level dedupe with variable-width chunk ID; can dedupe across volumes; com-pression ratio: 4-5x for pri-mary data, 10-20x for backup data Besides de-dupe and compres-sion, uses negotiated TCP optimi-zation and parallel-iza-tion Local snap-shots are auto tiered; cloud snap-shots are used for fast online re-store; cloud clones func-tion like off-site encryp-ted tape: can be cloned and mounted by any Stor-Simple de-vice using the same service ac-count SSDs and SAS drives for local pri-mary stor-age with au-to tiering and HA; ca-pacity from 10TB to 200TB
AES = Advanced Encryption Standard; HA = high availability; HDD = hard-disk drive; SAN = storage area network; SATA = Serial Advanced Technology Attachment; VM = virtual ma-chine
Recommended Reading
Some documents may not be available as part of your current Gartner subscription. "Competitive Landscape: Hybrid Storage Appliances, Gateway to Public Cloud" "Case Study: Reducing the Storage Cost via the Public Cloud"
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