Het is niet allemaal goud dat er blinkt bij ‘cloud storage’

4 september 2008

Opslag als een internetdienst ('cloud computing') gaat prat op relatief lage prijzen en voordelen als schaalbaarheid, flexibiliteit, eenvoudige toegang en toenemende marktpartijen. Maar het groeiende belang van de dienst betekent ook dat de tekortkomingen steeds meer bekend worden. 'Even as the technology has grown over the past two years, its success has been tempered with occasional problems like performance, reliability and support — highlighting issues that cloud storage vendors are working to address', zo zegt Bob Laliberte, analist bij Enterprise Storage Group. 'One downside is you get what you pay for, as performance isn't for Tier 1 applications. Service should at least be predictable, though reliability isn't on par with enterprise arrays. … The issue of network latency may always be an issue depending on a cloud's connectivity strength, but Web-based applications shouldn't necessarily be expected to perform like applications running in the corporate datacenter'. 'Cloud storage' is bedoeld om goedkopere, eenvoudiger te managen opties te bieden voor opslag, zodat organisaties makkelijker kunnen omgaan met de steeds duurder wordende opslag-infrastructuren en steeds toenemende capaciteits-, beveiligings- en retrieval vereisten. Een van de oorzaken van populariteit is dat hoewel de opslag-hardwarekosten aanzienlijk afnemen, dat niet genoeg is om de stijgende kosten van energiegebruik en datacentra te kunnen opvangen. Dat leidt er toe dat veel managers 'cloud storage' toepassen voor niet-kritieke gegevens. 'Another reason for increasing adoption is the flexibility aspect', zo zegt Laliberte. 'The ability to have access to my personal and potentially work information in any location and with the best possible connection can be a huge attraction. I don't have to wait to get home and fire up my PC to share files'.

Velen zijn zich niet bewust van de uitdagingen, zoals de ondersteuning en verwachtingen van de dienstverleningsovereenkomsten (DVO'S). 'Everyone wants affordable, accessible storage, but then they complain when there is an outage or they need support', zo zegt Greg Schulz, senior analist bij StorageIO. 'Look at Amazon's S3 outages that peppered its initial growth as a characteristic problem. Amazon's foray into cloud storage has done great things in pushing the concept into the mainstream, its initial stumbles also hurt the cause. In particular, Amazon's lack of SLAs at the time — nor dedicated user support beyond online forums — compounded the problems facing enterprises that found their data inaccessible for hours'. Amazon heeft sindsdien DVO's geformuleerd en biedt ondersteuning via email. Maar de ervaring zal wel enkele lessen hebben geleerd aan bedrijven die over 'cloud computing' aan het denken zijn. 'I would strongly recommend reviewing the SLAs and support in cloud service and determine if it meets the requirements for the project', zo zegt Schulz. 'Amazon's adoption of SLAs follows the tactics of earlier players in the space, such as Nirvanix'. Amazon's DVO stelt nu dat de dienst 'will store data durably, with 99.99 percent availability. There can be no single points of failure. All failures must be tolerated or repaired by the system without any downtime'. Beide analisten zeggen dat de beperkingen van betrouwbaarheid en ondersteuning de belangrijkste motivatoren moeten zijn voor wat wel en wat niet in de 'cloud' wordt opgeslagen. 'Right now, it is being used for a lot of Web 2.0 application backend needs, and for use with test and development', zegt Laliberte. 'Engineering departments, for example, find it easier to put down a credit card and get storage than to have it provisioned internally'. Het goede nieuws, zo zegt Schulz, is 'that cloud storage won't always face the same limitations it does today. Certainly, the current generation of cloud, managed and storage-as-a-service offerings are more robust and resilient than a few years ago. There is more flexibility and options in terms of interfaces and types of available services'. Met budgetbeperkingen, maar toch behoefte hebben aan grotere opslagcapaciteit kan dat voor veel bedrijven positieve effecten hebben. We are already seeing cloud computing evolving with cloud storage, and I expect that will continue, given the same caveat for SLAs and support', zegt Laliberte. 'Additionally, the concept will encourage more large companies to start building their own cloud storage environments internally to better service employees'. En Schulz vervolgt met: 'The current services will continue to evolve and become more scalable, flexible and resilient for broader adoption across different price bands and company sizes. …. The older outsourced storage model provides for a specific location within a host's datacenter, with direct access, and carries a tradition of offering SLAs. As storage cloud offerings build on those same aspects and works to improve reliability, users will begin to reap the same rewards — but at a much lower cost'.

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