CloudFounders: No More RAID

CloudFounders, a startup of former Terremark and SUN execs, also leverages a flash cache, but the building blocks are very different. Just like Nutanix, there is a VSA (Virtual Storage Appliance) that tries to make the best out of a local flash cache. The cool thing is that the backend, the second tier of storage, is not a traditional RAID based volume. The backend is either an object storage initiator that links to Amazon S3 or a storage device based upon erasure encoding called Distribute Storage System (DSS). Let's start with the DSS backend.

DSS is an object oriented storage system that uses “Bitspread”, an advanced and flexible erasure encoding system developed by the people of Amplidata. Amplidata is a startup with a mix of Belgian and US based infrastructure experts. Some of the directors are working for both CloudFounders and Amplidata. But there is a solid technical reason why CloudFounders chose to go with the Amplidata storage system. Bitspread is meant to be the “big storage alternative” to RAID.

As you probably know or have experienced hands-on, the current RAID implementations—RAID 5 and RAID 6—have reached their limitations now that we have terabyte disks. A few terabyte disks in RAID 5 can take days to rebuild. The result is that the RAID array performance and reliability is heavily degraded. RAID 6 is more reliable (although hardly 100%) but is not exactly a good performer for writes, which is another reason why VDI does not work well on a low end or midrange SAN.

“Bitspread” erasure encoding, also called Forward Error Correction Code (FEC), encodes data in “check-blocks”. The beauty is that you can configure the durability policy. In other words you can choose over how many disks these check-blocks should be spread and how many check-blocks you can lose before it becomes a problem. For example you could ask it to spread the datablock over 18 drives and tell the codec to make sure you can recover the original datablock from 12 check-blocks. So it's only if you lose more than 6 drives at once that you lose your data. As the codec requires only 12 of the check blocks to rebuild the original data object, a failure of two drives does not mean the rebuild should happen urgently. The rebuild can be done in the background at a very slow pace while the reliability stays high. You can also have the check-blocks spread over several storage modules, ensuring that you even survive a failure of a complete disk enclosure.

Bitspread: original data (yellow) is split up, encoded with high redundancy (green) and then spread over many disks and enclosures.

For those who are not convinced that the small startup Amplidata is onto something: Intel and Dr. Sam Siewert of Trellis Logic explain in this paper why it can even be mathematically proven that the Reed-Solomon based erasure codes of RAID 6 are a dead end road for large storage systems. The paper concludes:

"Amplida's Bitspread is an efficient, scalable and practical alternative to the stop-gap of combined RAID levels like 6+1."

And that is exactly the reason why CloudFounders chose to build their storage system on the Amplidata backend.

The DSS based on “Bitspread” works with objects and is thus not a block device. A volume driver must be installed that converts the DSS into a block device. This way the hypervisor can connect to an iSCSI target that is running on top of the volume driver, as an iSCSI target requires a block device and does not recognize the format of the DSS.

Bitspread is a lot more CPU intensive and needs more storage room than traditional RAID algorithms. To reduce the CPU impact, Amplidata leverages the SSE 4.2 capabilities of the latest Xeons. As Bitspread copes so well with disk failures, it is natural to use relatively slow SATA disks, which negates the capacity disadvantage compared to RAID 6. Decent media transfer can still be achieved as the DSS typically spreads the check-blocks over many disks.

Nutanix: No More SAN CloundFounders: Cloud Storage Router
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  • pjkenned - Tuesday, August 6, 2013 - link

    Hi Johan, one thing to be clear about is that the dollars you are quoting in this article are off by a huge margin. Enterprise storage is one of the most highly discounted areas of technology. Happy to chat more on this subject. Patrick @STH
  • name99 - Tuesday, August 6, 2013 - link

    Ahh, the never-ending whine of the Enterprise sale man, who desperately wants to have it both ways --- to be able to charge a fortune and simultaneously to claim that he's not charging a fortune. Good luck with that --- there is, after all, a sucker born every minute.

    But let's get one thing straight here. If your organization refuses to publish the actual prices at which it sells, then you STFU when people report the prices that ARE published, not the magic secret prices that you claim exist but neither you nor anyone else are ever allowed to actually mention them. You don't get to have it both ways.
    AnandTech and similar blogs are not in the business of sustaining your obsolete business model and its never-ending lies about price...
  • enealDC - Tuesday, August 6, 2013 - link

    Thank you!!! lol
  • JohanAnandtech - Tuesday, August 6, 2013 - link

    You can not blame a company to do whatever they can to protect their business model, but your comment is on target. The list versus street price models reminds of techniques of salesman on the street in touristic areas: they charge 3 times too much, and you end up with a 50% discount. The end result is that you are still ripped off unless you have intimate knowledge.
  • nafhan - Tuesday, August 6, 2013 - link

    My experience with stuff like this is that the low prices are geared towards locking you into their products and getting themselves in the door. As soon as these companies feel certain that changing to a different storage tech would be prohibitively expensive for you, the contract renewal price will go through the roof.

    In other words, that initial price may actually be very good and very competitive. Just don't expect to get the same deal when things come up for contract renewal.
  • equals42 - Saturday, August 17, 2013 - link

    You shouldn't be making enterprise purchasing decisions unless you have intimate knowledge and have done the necessary research.
  • pjkenned - Tuesday, August 6, 2013 - link

    So three perspectives:

    First - I have been advocating open storage projects for years. I do think we are moving to 90%+ of the market being 4TB drives and SSDs and SDS is a clear step in this direction. I don't sell storage but have been using open platforms for years precisely because of the value I can extract through the effort of sizing the underlying hardware.

    Second - Most of the big vendors are public companies. It isn't hard to look at gross margin and figure out ballpark what average discounts are. Most organizations purchasing this type of storage have other needs. The market could push for lower margins so my sense is that the companies buying this class of storage are not just paying for raw storage.

    Third - vendors are moving the direction of lower discounts at the low end. Published list prices there are much closer to actual as the discounting trend in the industry is towards lower list prices.

    Not to say that pricing is just or logical, but then again, it is a large industry that is poised for a disruptive change. One key thing here is that I believe you can get pricing if you just get a quote. This is the same as other enterprise segments such as the ERP market.
  • equals42 - Saturday, August 17, 2013 - link

    I'll not ask you to STFU as you eloquently abbreviated it. Though in general I believe people ultimately charge what they believe the market will pay.

    Yes, list prices are generously overpriced in the IT industry. But to ask EMC or IBM to tell you how much they really charge for things is stupid. That's a negotiated rate between them and their customer. BofA or WalMart isn't going to disclose how much they pay for services. Their low negotiated price helps drive efficiencies to better compete with rivals. Heck, ask Kelloggs how much Target pays per box for cereal vs WalMart. No way in hell they're going to tell you. You think a SMB is going to get the same price as Savvis or Bank of America? They can ask for it but good luck. I sense some naiveté in your response.

    In essence you're complaining about how inflated the list is vs what the average customer pays. That's a game played out based on supply and demand, market expectations and the blended costs of delivering products.
  • prime2515103 - Tuesday, August 6, 2013 - link

    "Note that the study does not mention the percentage customer stuck in denial :-)."

    I don't mean to be a jerk or anything, but I can't believe I just read that on Anandtech. It's not the grammar either. A smiley? Good grief...
  • JohanAnandtech - Tuesday, August 6, 2013 - link

    I fixed the sentence, but left the smiley in there. My prerogative ;-)

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