Amazon EFS stuck in beta, lacks native Windows support

Amazon's long-awaited Elastic File System is expected to hit the market soon, but it won't natively support Windows or high-performance workloads.

AWS customers are eager to get their hands on Amazon EFS sooner rather than later, but so far the preview version lacks native Windows support, and some beta testers say it doesn't offer the kind of performance they're used to with on-premises storage systems.

Amazon Elastic File System (EFS) has been subject to a prolonged beta period since last April. In June, Amazon officials predicted that the cloud file storage service would be available at least in more regions than US-West (Oregon) by the end of the last summer.

AWS shops are eager to get Amazon EFS into production because it fills an important niche in the company's storage portfolio. Amazon's Elastic Block Store (EBS) is mountable by only one machine at a time; Amazon Simple Storage Service (S3) can be accessed by more than one machine at a time, but doesn't expose the file system that many traditional enterprise applications expect.

The preview is only working with Linux file systems and we needed it to work with Samba so that it could mount to Windows file shares.
AWS partner

Without EFS, users potentially would have to rewrite those applications to interface with S3's object-based storage, or mount EBS volumes to individual EC2 instances, rather than sharing storage.  In other words, Amazon EFS could make some hard-to-port enterprise applications 'cloudable,' opening new markets for AWS and new cloud use cases for enterprise IT shops.

Amazon declined to comment on the reasons for the long beta period, or when users can expect Amazon EFS to become generally available.

"Given the scale of AWS' business, we don't release services before we think they're ready," said an Amazon spokesperson. "We have a lot of customer feedback that they're excited about EFS, and as we continue to evolve the preview, we're confident that EFS performance and customer demand will be quite strong." 

Amazon EFS preview doesn't support Windows instances

An Amazon rep said at the event last June that access to Amazon EFS could be controlled through standard Windows and Linux directory and file-level permissions, and the Amazon EFS product page advertises that "the applications and tools that you use today work seamlessly with Amazon EFS." However, Amazon has communicated through its documentation that the file system, based on NFSv4, doesn't natively support Windows instances.

This caused at least one partner to leave the beta last month.

"The preview is only working with Linux file systems and we needed it to work with Samba so that it could mount to Windows file shares," the partner said. Amazon's documentation points to a private forum for updates on Windows support, but according to the partner, when last he looked in December, "there were no instructions for mounting with Windows."

Microsoft reps said that the company recommends connecting Windows to a Linux AMI in order to connect to NFS using PuTTY, an open-source utility. Amazon reps said this workaround is not recommended for anything other than connecting to an EC2 instance from Windows*, and Microsoft officials stopped short of explicitly saying it would support customers who put it into use. Instead, Microsoft pledged to work with the user to help resolve any issues. Windows Server 2012 can natively support NFS 4.1, but not NFSv4, according to Microsoft's documentation.

Microsoft officials would not comment on whether it would offer native support for EFS. According to one source close to the company, Microsoft skipped over support for the NFS v4.0 version because v 4.1 is more modern, supporting a variety of higher-end capabilities that are more desired by heterogeneous enterprises, including complex clustering and some cloud technologies.

"[Microsoft is] going to do NFS in a way that makes sense for them," the source said. "People think they should make business decisions in users' best interests, but vendors can't do exclusively what is good for users, when it might prove bad for the vendor."

The jump from v4.0 to v4.1 may appear to be incremental to some, according to the source, but, in fact, some additions to v4.1 make them "two very different code bases." If Microsoft delivered support for v4.0, it would be a "crude implementation," the source said. "If you have tried to use NFS from a Windows system, for instance, it's like walking around with one leg cut off from the knee down."

Other EFS beta testers said they gave up on the beta last year, citing poor I/O performance across Availability Zones. More recent participants in the beta say the performance, advertised at 50 mebibytes per second (MiB/s) for a 1 terabyte file system in Amazon's documentation -- which translates to 420 Mbps -- is adequate for their needs. They also speculate that AWS is working to get pricing details finalized before release. Currently, pricing is set at $0.30 per GB with the preview version.

"My understanding is that they hadn't hit the [price /performance] ratio they wanted to hit, and that's something that just needed some engineering work," said a vice president at a company in the Pacific Northwest that's currently testing EFS. "If that's really true, then this issue could be solved as soon as engineers hit the mark."

Another source close to Amazon said this week that general availability is about a month away.

Open questions about Amazon EFS performance

Performance on EFS is burstable to higher throughput rates than the 420 Mbps baseline, depending on the size of the file system, according to Amazon's documentation. The file system can burst up to 100 MiB/s, or 838 Mbps, closer to Gigabit Ethernet speeds, and a 10 TB file system can burst up to 1000 MiB/s, or 8.38 Gbps.*

"We have found performance to be decent but not anywhere close to an EBS-based storage system in terms of consistency or ease of control," said the vice president who is beta testing Amazon EFS. EBS offers provisioned IOPS, which can provide up to 20,000 guaranteed IOPS, or 320 MBps throughput (2.56 Gbps) per volume.

However, even the performance of EBS -- and all cloud storage, for that matter -- pales in comparison to the performance that's achievable with on-premises systems.

"For us, we especially feel the contrast, because our private cloud typically delivers sub-millisecond response for reads and writes, and upwards of 600,000 IOPs to any given instance, while our AWS instances often have several orders of magnitude slower performance," said the vice president.

There is also an open question around the performance of Amazon EFS for IOPS in an environment with many small files. At last year's re:Invent conference, presentations that mentioned the use of Amazon EFS at Walt Disney Animation Studios and Sony emphasized that Amazon EFS was well-suited for I/O with large files.

Analysts, however, say that small file I/O, which results in many queries on metadata, can be an Achilles' heel for NFS in general -- regardless of whether the file system runs on Amazon.

"If I'm building a Web application, it's not two EC2 instances, it's 200," said Mike Matchett, analyst at the Taneja Group in Hopkinton, Mass., and a TechTarget contributor. "They're coming and going, and if you think of the metadata operations that happen with NFS, it's not designed for either that scale or that quantity of meta-level queries that go on. My guess is that could be a bottleneck."

Amazon is looking to solve some very difficult problems with a file system that is elastically scalable as well as highly available and performant, according to another AWS partner who is part of the Amazon EFS preview.

"It's essentially taking all of Amazon's technology and trying to build a locking, synchronous, strong consistency model file store off of an entire platform that is designed in the exact opposite direction," the partner said.

The more files there are, and the more clients trying to access them, means more overhead  to maintain this file store, according to this partner. That situation is further compounded by the fact that multiple copies of each file also must be maintained for high availability purposes.

"It is a matrix effect ... it's very much about the ability of that metadata store to address files," he said.

"I would hope that they're getting close," the partner added. "I don't think that this is an unsolvable problem, especially with the likes of some of the engineers that I know who are working on it."

Users who don't want to wait for general availability or for Windows support in Amazon EFS, particularly at the low end of the market, can go with other NAS choices in the AWS Marketplace, such as NetApp Inc.'s Cloud ONTAP or SoftNAS Inc.'s self-named product. Both products offer iSCSI, NFS and CIFS support. SoftNAS is priced at $0.08 per GB per month, in addition to underlying EC2 and EBS costs.*

* - Statement changed after initial publication.

Beth Pariseau is senior news writer for SearchAWS. Write to her at [email protected] or follow @PariseauTT on Twitter.

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