Tag Archives: Filesystem

The engineering of Elastifile

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[Preamble: I was a delegate of Storage Field Day 12. My expenses, travel and accommodation were paid for by GestaltIT, the organizer and I was not obligated to blog or promote the technologies presented in this event]

When it comes to large scale storage capacity requirements with distributed cloud and on-premise capability, object storage is all the rage. Amazon Web Services started the object-based S3 storage service more than a decade ago, and the romance with object storage started.

Today, there are hundreds of object-based storage vendors out there, touting features after features of invincibility. But after researching and reading through many design and architecture papers, I found that many object-based storage technology vendors began to sound the same.

At the back of my mind, object storage is not easy when it comes to most applications integration. Yes, there is a new breed of cloud-based applications with RESTful CRUD API operations to access object storage, but most applications still rely on file systems to access storage for capacity, performance and protection.

These CRUD and CRUD-like APIs are the common semantics of interfacing object storage platforms. But many, many real-world applications do not have the object semantics to interface with storage. They are mostly designed to interface and interact with file systems, and secretly, I believe many application developers and users want a file system interface to storage. It does not matter if the storage is on-premise or in the cloud.

Let’s not kid ourselves. We are most natural when we work with files and folders.

Implementing object storage also denies us the ability to optimally utilize Flash and solid state storage on-premise when the compute is in the cloud. Similarly, when the compute is on-premise and the flash-based object storage is in the cloud, you get a mismatch of performance and availability requirements as well. In the end, there has to be a compromise.

Another “feature” of object storage is its poor ability to handle transactional data. Most of the object storage do not allow modification of data once the object has been created. Putting a NAS front (aka a NAS gateway) does not take away the fact that it is still object-based storage at the very core of the infrastructure, regardless if it is on-premise or in the cloud.

Resiliency, latency and scalability are the greatest challenges when we want to build a true globally distributed storage or data services platform. Object storage can be resilient and it can scale, but it has to compromise performance and latency to be so. And managing object storage will not be as natural as to managing a file system with folders and files.

Enter Elastifile.

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MASSive, Impressive, Agile, TEGILE

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Ah, my first blog after Storage Field Day 6!

It was a fantastic week and I only got to fathom the sensations and effects of the trip after my return from San Jose, California last week. Many thanks to Stephen Foskett (@sfoskett), Tom Hollingsworth (@networkingnerd) and Claire Chaplais (@cchaplais) of Gestalt IT for inviting me over for that wonderful trip 2 weeks’ ago. Tegile was one of the companies I had the privilege to visit and savour.

In a world of utterly confusing messaging about Flash Storage, I was eager to find out what makes Tegile tick at the Storage Field Day session. Yes, I loved Tegile and the campus visit was very nice. I was also very impressed that they have more than 700 customers and over a thousand systems shipped, all within 2 years since they came out of stealth in 2012. However, I was more interested in the essence of Tegile and what makes them stand out.

I have been a long time admirer of ZFS (Zettabyte File System). I have been a practitioner myself and I also studied the file system architecture and data structure some years back, when NetApp and Sun were involved in a lawsuit. A lot of have changed since then and I am very pleased to see Tegile doing great things with ZFS.

Tegile’s architecture is called IntelliFlash. Here’s a look at the overview of the IntelliFlash architecture:

Tegile IntelliFlash Architecture

So, what stands out for Tegile? I deduce that there are 3 important technology components that defines Tegile IntelliFlash ™ Operating System.

  • MASS (Metadata Accelerator Storage System)
  • Media Management
  • Inline Compression and Inline Deduplication

What is MASS? Tegile has patented MASS as an architecture that allows optimized data path to the file system metadata.

Often a typical file system metadata are stored together with the data. This results in a less optimized data access because both the data and metadata are given the same priority. However, Tegile’s MASS writes and stores the filesystem metadata in very high speed, low latency DRAM and Flash SSD. The filesystem metadata probably includes some very fine grained and intimate details about the mapping of blocks and pages to the respective capacity Flash SSDs and the mechanical HDDs. (Note: I made an educated guess here and I would be happy if someone corrected me)

Going a bit deeper, the DRAM in the Tegile hybrid storage array is used as a L1 Read Cache, while Flash SSDs are used as a L2 Read and Write Cache. Tegile takes further consideration that the Flash SSDs used for this caching purpose are different from the denser and higher capacity Flash SSDs used for storing data. These Flash SSDs for caching are obviously the faster, lower latency type of eMLCs and in the future, might be replaced by PCIe Flash optimized by NVMe.

Tegile DRAM-Flash Caching

This approach gives absolute priority, and near-instant access to the filesystem’s metadata, making the Tegile data access incredibly fast and efficient.

Tegile’s Media Management capabilities excite me. This is because it treats every single Flash SSD in the storage array with very precise organization of 3 types of data patterns.

  1. Write caching, which is high I/O is focused on a small segment of the drive
  2. Metadata caching, which has both Read and Write I/O  is targeted to a slight larger segment of the drive
  3. Data is laid out on the rest of the capacity of the drive

Drilling deeper, the write caching (in item 1 above) high I/O writes are targeted at the drive segment’s range which is over-provisioned for greater efficiency and care. At the same time, the garbage collection(GC) of this segment is handled by the respective drive’s controller. This is important because the controller will be performing the GC function without inducing unnecessary latency to the storage array processing cycles, giving further boost to Tegile’s already awesome prowess.

In addition to that, IntelliFlash ™ aligns every block and every page exactly to each segment and each page boundary of the drives. This reduces block and page segmentation, and thereby reduces issues with file locality and free blocks locality. It also automatically adjust its block and page alignments to different drive types and models. Therefore, I believe, it would know how to align itself to a 512-bytes or a 520-bytes sector drives.

The Media Management function also has advanced cell care. The wear-leveling takes on a newer level of advancement where how the efficient organization of blocks and pages to the drives reduces additional and often unnecessary erase and rewrites. Furthermore, the use of Inline Compression and Inline Deduplication also reduces the number of writes to drives media, increasing their longevity.

Tegile Inline Compression and Deduplication

Compression and deduplication are 2 very important technology features in almost all flash arrays. Likewise, these 2 technologies are crucial in the performance of Tegile storage systems. They are both inline i.e – Inline Compression and Inline Deduplication, and therefore both are boosted by the multi-core CPUs as well as the fast DRAM memory.

I don’t have the secret sauce formula of how Tegile designed their inline compression and deduplication. But there’s a very good article of how Tegile viewed their method of data reduction for compression and deduplication. Check out their blog here.

The metadata of data access of each and every customer is probably feeding into their Intellicare, a cloud-based customer care program. Intellicare is another a strong differentiator in Tegile’s offering.

Oh, did I mentioned they are unified storage as well with both SAN and NAS, including SMB 3.0 support?

I left Tegile that afternoon on November 5th feeling happy. I was pleased to catch up with Narayan Venkat, my old friend from NetApp, who is now their Chief Marketing Officer. I was equally pleased to see Tegile advancing ZFS further than the others I have known. With so much technological advancement and more coming, the world is their oyster.

Ocarina rising

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After more than a year since Dell acquired Ocarina Networks, it has finally surfaced last week in the form of Dell DX Object Storage 6000G SCN (Storage Compression Node).

Ocarina is a content-aware storage optimization engine, and their solution is one of the best I have seen out there. Its unique ECOsystem technology, as described in the diagram below, is impressive.

Unlike most deduplication and compression solutions out there, Ocarina Networks solution takes storage optimization a step further.  Ocarina works at the file level and given the rise and crazy, crazy growth of unstructured files in the NAS space, the web and the clouds, storage optimization is one priority that has to be addressed immediately. It takes a 3-step process – Extract, Correlate and Optimize.

Today’s files are no longer a flat structure of a single object but more of a compounded file where many objects are amalgamated from different sources. Microsoft Office is a perfect example of this. An Excel file would consists of objects from Windows Metafile Formats, XML objects, OLE (Object Linking and Embedding) Compound Storage Objects and so on. (Note: That’s just Microsoft way of retaining monopolistic control). Similarly, a web page is a compound of XML, HTML, Flash, ASP, PHP object codes.

In Step 1, the technology takes files and breaks it down to its basic components. It is kind of like breaking apart every part of a car down to its nuts and bolt and layout every bit on the gravel porch. That is the “Extraction” process and it decodes each file to get the fundamental components of the files.

Once the compounded file object is “extracted”, identified and indexed, each fundamental object is Correlated in Step 2. The correlation is executed with the file and across files under the purview of Ocarina. Matching and duplicated objects are flagged and deduplicated. The deduplication is done at the byte-level, unlike most deduplication solutions that operate at the block-level. This deeper and more granular approach further reduces the capacity of the storage required, making Ocarina one of the most efficient storage optimization solutions currently available. That is why Ocarina can efficiently reduce the size of even zipped and highly encoded files.

It takes this storage optimization even further in Step 3. It applies content-aware compactors for each fundamental object type, uniquely compressing each object further. That means that there are specialized compactors for PDF objects, ZIP objects and so on. They even have compactors for Oil & Gas seismic files. At the time I was exposed to Ocarina Networks and evaluating it, it had about 600+ unique compactors.

After Dell bought Ocarina in July 2010, the whole Ocarina went into a stealth mode. Many already predicted that the Ocarina technology would be integrated and embedded into Dell’s primary storage solutions of Compellent and EqualLogic. It is not there yet, but will likely be soon.

Meanwhile, the first glimpse of Ocarina will be integrated as a gateway solution to Dell DX6000 Object Storage. DX Object Storage is a technology which Dell has OEMed from Caringo. DX6000 Object Storage (I did not read in depth) has the concept of the old EMC Centera, but with a much newer, and more approach based on XML and HTTP REST. It has published an open API and Dell is getting ISV partners to develop their applications to interact with the DX6000 including Commvault, EMC, Symantec, StoredIQ are some of the ISV partners working closely with Dell.

(24/10/2011: Editor note: Previously I associated Dell DX6000 Object Storage with Exanet. I was wrong and I would like to thank Jim Dtuton of Caringo for pointing out my mistake)

Ocarina’s first mission is to reduce the big, big capacities in Big Data space of the DX6000 Object Storage, and the Ocarina ECOsystem technology looks a good bet for Dell as a key technology differentiator.