Going Native CIFS

A recent comment on this blog got me thinking, and this post is the result. The commenter, who identified him or herself only as “Sto Rage” asked: “When can we expect native CIFS support on the Ocarina platforms? The current implementation is outright clunky. So until you have a working CIFS implementation, I don’t think you can compete with NetApp. You may get better compression results, but it works only for NFS data.”

It’s a good point to raise–although I disagree with the “clunky” characterization. But as to the CIFS issue, I wish the answer was as simple as “it’s in the next release,” but this is actually one of the more complex and interesting topics in storage. So hold on to your hats, I’m going to go through Ocarina and CIFS in some detail.

Here’s the short answer: We give you native CIFS support on EMC, BlueArc, HDS, and HP. Several more NAS vendors will be putting “Ocarina Inside” soon. We give you native CIFS support if you can use our Native Format Optimization. For those customers who use our appliance as a CIFS proxy, we provide good but not perfect CIFS support today, with a roadmap of continual improvement, including the possibility of a native CIFS stack inside the appliance in the first half of next year.

Here’s the longer and more detailed answer.

Ocarina can be deployed in one of three ways:

“Ocarina Inside”: Ocarina is embedded inside or alongside a NAS vendor’s solution.
Ocarina Appliance: A split-band appliance
Ocarina Native Format Optimization (NFO): files are optimized in their native format

Each one of these deployment options has different implications for the CIFS client.

In the “Ocarina Inside” case, the NAS vendor handles all the protocol stacks, and the client gets the full, rich native CIFS implementation of each vendor. Ocarina only uses dedupe or compress for the data stream.  We are not involved in the protocol traffic at all.  Examples of “Ocarina Inside” are EMC Celerra, HP Enterprise NAS, BlueArc, and HDS HNAS.  Additional “Ocarina Inside” partners will be announced soon. This is the best form of integration, because it makes deduplication and compression completely transparent to users and applications, and lets each storage vendor deliver all their full value-add, including in the CIFS protocol stack.

In the Ocarina Appliance case, Ocarina’s optimization happens out of the customer data path, but in order to expand files to their original state upon user access, the Ocarina intercepts read requests in-band. If an I/O (over CIFS or NFS) is to an Ocarina-optimized file, we step in, rehydrate the file, and pass it on to the user. This involves being a proxy for NFS and CIFS (and other protocols including WebDAV and http).   It’s fairly easy to be a proxy for NFS and http, but CIFS is more challenging. Ocarina has done a lot of infrastructure work to ensure that we preserve all of the Windows file attributes necessary for good CIFS integration – ACL’s, Extended Attributes, Alternate Data Streams, Windows share modes and oplocks, etc.

However, we have not written our own CIFS protocol, so our Windows semantic completeness is only as good as the protocol implementation that we sit on. On the appliance, today, that is Samba. Samba has improved a great deal over the last few years, but it is still not a “native” implementation of CIFS. While many storage vendors use variants of Samba for their CIFS stack, it is admittedly not as rich as, say, CIFS on Windows (the only true native CIFS) or CIFS on NetApp.

Ocarina has multiple customers who have implemented Ocarina using both NFS and CIFS on our appliance, and while there may be corner cases where it’s just not as good as the richest CIFS implementations, it’s not “outright clunky” either. There is room for improvement, though, and this is an area of primary focus for our next set of releases. It’s probably a topic for an entirely separate post, but there is a lot going on in the CIFS world these days, and we see some pretty exciting opportunities emerging in this space.

The third case is “Native Format Optimization.” This is a special use of Ocarina where we take certain rich media file types – photos, images and video – and compress them in a special way. What we do is compress them, but have the output be a new, smaller file but in the same native format it started out in. We’ll take a JPEG photo, compress it, and produce as output another perfectly formed JPEG photo….just smaller. The same is true for example for Flash videos. Now in this case, there is no need for a decompressor or for Ocarina to be in the read path or on the protocol at all. We can read files from your NetApp, shrink them, write them back on to your NetApp and Ocarina need not be involved at all when users or applications go to access those files.

In fact, we have a major Fortune 100 company who uses our technology on a large farm of NetApp filers in just this way. In this case, users access the files over all the native protocols that the NetApp supports, including NFS, “native” CIFS, and dual protocol support (NFS and CIFS at the same time). NFO only applies to certain file types, and so it is not the right fit for every data set. However, it is worth pointing out that one of the complaints you see about other deduplication and compression solutions for primary storage is that you save space at the cost of slowing performance down. With NFO, since there is NO decompression, just a smaller file in its original native format, performance is actually and always better.  There are simply fewer bytes to read off disk, fewer bytes to move over a network and no extra hop or decompression step to go through.  It’s a fantastic solution for customers with lots of image, photo, or video data, and it works with all native CIFS implementations.

So there you have it. CIFS support in more detail than you probably ever dreamed or imagined. We look forward to your further comments.