Archive for 21st March 2016

You had me at Tiered Non-Volatile Memory!

Memory isn’t cheap! Despite the falling costs and increasing sizes of DRAM DIMMS, it’s still damned expensive compared to most non-volatile media at a price per GB. What’s more frustrating is that often you buy all of this expensive RAM, assign it to your applications, and find later through detailed monitoring, that only a relatively small percentage is actually being actively used.

For many years, we have had technologies such as paging, which allow you to maximise the use of your physical RAM, by writing out the least used pages to disk, freeing up RAM for services with current memory demand. The problem with paging is that it is sometimes unreliable, and when you do actually need to get that page back, it can be multiple orders of magnitude slower returning it from disk.

Worse still, if you are running a workload such as virtual machines and the underlying host becomes memory constrained, a hypervisor may often not have sufficient visibility of the underlying memory utilisation, and as such will simply swap out random memory pages to a swap file. This can obviously have significant impact on virtual machine performance.

More and more applications are being built to run in memory these days, from Redis to Varnish, Hortonworks to MongDB. Even Microsoft got on the bandwagon with SQL 2014 in-memory OLTP.

One of the companies we saw at Storage Field Day ,  Plexistor, told us that can offer both tiered posix storage and tiered non-volatile memory through a single software stack.

The posix option could effectively be thought of a bit like a non-volatile, tiered RAM disk. Pretty cool, but not massively unique as RAM disks have been around for years.

The element which really interested me was the latter option; effectively a tiered memory driver which can present RAM to the OS, but in reality tier it between NVDIMMs, SSD and HDDs depending on how hot / cold the pages are! They will also be able to take advantage of newer bit addressable technologies such as 3D XPoint as they come on the market, making it even more awesome!

PlexistorArch.jpg

Plexistor Architecture

All of this is done through the simple addition of their NVM file system (i.e. device driver) on top of the pmem and bio drivers and this is compatible with most versions of Linux running reasonably up to date kernel versions.

It’s primarily designed to work with some of the Linux based memory intensive apps mentioned above, but will also work with more traditional workloads as well, such as MySQL and the KVM hypervisor.

Plexistor define their product as “Software Defined Memory” aka SDM. An interesting term which is jumping on the SDX bandwagon, but I kind of get where they’re going with it…

SDM_vs_SDS2.png

Software Defined Memory!

One thing to note with Plexistor is that they actually have two flavours of this product; one which is based on the use of NVRAM to provide a persistent store, and one which is non-persistent, but can be run on cloud infrastructures, such as AWS. If you need data persistence for the latter, you will have to do it at the application layer, or risk losing data.

If you want to find out a bit more about them, you can find their Storage Field Day presentation here:
Plexistor Presents at Storage Field Day 9

Musings…
As a standalone product, I have a sneaking suspicion that Plexistor may not have the longevity and scope which they might gain if they were procured by a large vendor and integrated into existing products. Sharon Azulai has already sold one startup in relatively early stages (Tonian, which they sold to Primary Data), so I suspect he would not be averse to this concept.

Although the code has been written specifically for the Linux kernel, they have already indicated that it would be possible to develop the same driver for VMware! As such, I think it would be a really interesting idea for VMware to consider acquiring them and integrating the technology into ESXi. It’s generally recognised as a universal truth that you run out of memory before CPU on most vSphere solutions. Moreover, when looking in the vSphere console we often see that although a significant amount of memory is allocated to VMs, often only a small amount is actually active RAM.

The use of Plexistor technology with vSphere would enable VMware to both provide an almost infinite pool of RAM per host for customers, as well as being able to significantly improve upon the current vswp process by ensuring hot memory blocks always stay on RAM and cold blocks are tiered out to flash.

plexistorvmware

The homelab nerd in me also imagines an Intel NUC with 160GB+ of addressable RAM per node! 🙂

Of course the current licensing models for retail customers favour the “run out of RAM first” approach as it sells more per-CPU licenses, however, I think in the long term VMware will likely move to a subscription based model, probably similar to that used by service providers (i.e. based on RAM). If this ends up being the approach, then VMware could offer a product which saves their customers further hardware costs whilst maintaining their ESXi revenues. Win-Win!

Further Reading
One of the other SFD9 delegates had their own take on the presentation we saw. Check it out here:

Disclaimer/Disclosure: My flights, accommodation, meals, etc, at Storage Field Day 9 were provided by Tech Field Day, but there was no expectation or request for me to write about any of the vendors products or services and I was not compensated in any way for my time at the event.

Violin Memory have cool technology, but do they have a future? I hope so!

Since visiting Violin Memory at Storage Field Day 8, it has taken me a while to get around to writing this post, and I guess the reason is because I am both frustrated, and a little bit sad.

They were the first guys who (for me at least) truly tamed the beast that is flash storage, packed it up into a blisteringly fast product with insanely low latencies, and released it into the big wide world.

An organisation I worked at took that product and threw thousands of desktop users at it, a number of very busy SQL TempDBs, and some other frankly evil workloads. It didn’t even blink an eye! With Violin Storage on the back, I have seen RDS desktop customers stress test the platform with up to 100 users in a single VM!

The thing that makes me sad is that to date, Violin have not yet turned a profit.

This is not some upstart company out of the boondocks! This is a mature company, founded in 2005, who provide their product to some of the biggest enterprises in the world. Yet so far they have not managed to make a penny!

Anyway, there are other guys in the industry who are far better at financial analysis than me (for example Justin Warren did a post on this very subject just last week). So I will leave it to them try to work out why this is the case, because I like to talk tech!

Violin Memory

Looking at the latest incarnation, once again Violin have “evolutionized” [sic] something which is technically very impressive.

  • The original Violin OS has been given the boot and has been replaced by something they call Concerto OS, which blends elements of the original software with some updated features. In development is also support for a multi-controller configuration beyond the current dual, though this is obviously not GA yet.
  • The new dual controller Flash Storage Platform supports FC, iSCSI and Infiniband, as well as RDMA and ROCE.
  • It is all packaged in a 3U appliance with up to 64 redundant flash modules.
  • Thanks to their own custom backplane design, it is capable of 10-12GB/sec of throughput!
  • At 100% sustained writes they have measured 400,000 IOPSat RAID5, which is more than many of their competitors can achieve with 100% reads!It should be noted that this was on the performance model, which does not support dedupe.

All in all the new solution just screams FAST! In fact, I’m surprised they didn’t paint a red stripe down the side of the chassis!

low latency

So why on earth are Violin not ruling the AFA world right now? As a frickin cool technology with hyper speed storage, they deserve to be up there at the very least!

If I had to hazard a guess, it’s because for most companies, good is good enough.

With the smorgasbord of All Flash Arrays available today, if you don’t need latency measured in microseconds and massive IOPS/bandwidth, then you have a huge array of choices (pardon the pun). At that point features, price and support become more important than straight line drag racer performance.

If Violin want to compete with the general market whilst servicing their high-speed clients, then they need to concentrate on continuing to developing a wider range of data services and providing entry-level options to consume their products. The last thing you want to do is lose business just because you were missing a check box in an RFP…

If Violin can stop burning cash and break even, then perhaps they have a future. I for one, hope so!

If you want to catch Violin’s presentation from SFD8, check them out here:
http://techfieldday.com/appearance/violin-memory-presents-at-storage-field-day-8/

They will also be presenting again at SFD9 this week, and I’m looking forward to finding out what they plan to do next!

Further Reading
Some of the other SFD8 delegates have their own takes on the presentation we saw. Check them out here:

Disclaimer/Disclosure: My flights, accommodation, meals, etc, at Storage Field Day 8 were provided by Tech Field Day, but there was no expectation or request for me to write about any of the vendors products or services and I was not compensated in any way for my time at the event.

Pure Storage goes All Cloudy

Conversations (and arguments) are prevelant in the industry today about moving to the cloud, be it public cloud, private cloud or hybrid cloud.

People are developing into the usual fervent “religious” groups depending on their personal biases and use cases, and today Pure Storage joined the discussion by announcing a new feature for their FlashStack product. Working in partnership with Equinix, they will enable you to effectively colo a replicated FlashStack device in an Equinix DC, then use it to mount volumes via iSCSI, straight into your instances on AWS and Azure.

FlashStackHybrid.png

This is an interesting solution and having discussed this with several other guys at Pure Accelerate, the general impression is positive for two main reasons/uses:

  • Legacy solutions which depend on traditional enterprise infrastructure / storage patterns and performance.
  • As a sales enabler for Pure – Ticking checkboxes for FlashStack when”Is it cloud integrated?” comes up in an RFP.

It’s a cool idea, but personally, I am still struggling to find a really compelling use case for this, and I do slightly worry for Pure that they are providing an easy on-ramp to the public cloud for their customers. Once the compute is up there, comfort with the public cloud grows, and applications are refactored to be more cloud-compatible, the primary storage will undoubtedly follow. Pure do run the risk eroding a percentage of their customer base in the long term.

I guess only time will tell, but I hope this little gamble does not turn around to bite Pure in the rear later!

Hybrid FlashStack integration is available on Azure today, with AWS coming soon…

Disclaimer/Disclosure: My accommodation, meals and event entry to Pure Accelerate were provided by Pure Storage, and my flights were provided by Tech Field Day, but there was no expectation or request for me to write about any of the products or services and I was not compensated in any way for my time at the event.

Pure Storage – Now available in Petite

Pure Storage are probably one of the best known “All Flash” vendors in the industry today, but one of the things which has set the bar a little high for smaller organisations to get a slice of this speedy action, is the price.

Well, the good news is that for customers with smaller projects or simply smaller budgets, a Pure AFA is now within reach!

At Pure Accelerate today, along with their new FlashStack and FlashBlades, Pure announced a mini version of their ever popular M-series arrays, the FlashArray //M10.

This new array is fully featured, comes in the same form factor and with all of the same software, support, etc as the bigger models (//M20, //50, //70) but at a lower entry point of <$50k list including the first year of support. Not only that, but it is in-place non-disruptively upgradeable to the larger controller models later, all the way up to the //M70, so it is possible to buy in at this cheapest level and upgrade as business needs dictate later.

The only main differences between te //M10 and other Pure models is the lack of expansion ports on the controllers (you need at least an //M20 if you want to add shelves), and reduced compute / DRAM capacity.

m10.png

Specs are pretty much in line with the rest of the arrays in the range, with the //M10 coming in at 5TB / 10TB raw. Depending on your workloads, after dedupe and compression, this could be up to the stated useable (12.5TB/25TB). Mileage, as always, may vary! This is the perfect quantity for many use cases, including small to medium sized VDI environments, critical databases, etc. I suspect the //M10 may even find its way into some larger enterprises who’s internal processes often dictate that every project has its own budgets and its own pool of dedicated resources!

Lastly, and possibly most importantly to small businesses who may not have full time staff dedicated to managing storage, Pure’s monitoring and upgrade services are all included as well, via Pure1.

I think this is a positive step for the company and will help to engage with their customer base earlier in the organisational lifecycle, and when combined with their unique and very sticky Evergreen Storage offering, it will enable them to keep customers for life!

Disclaimer/Disclosure: My accommodation, meals and event entry to Pure Accelerate were provided by Pure Storage, and my flights were provided by Tech Field Day, but there was no expectation or request for me to write about any of the products or services and I was not compensated in any way for my time at the event.

%d bloggers like this: