Tag Archive for TFD

Why are storage snapshots so painful?

Have you ever wondered why we don’t use snapshots more often than about every 5-15 minutes in most solutions, and in many others, a lot less often than that?

It’s pretty simple to be honest… The biggest problem with taking snapshots is quiescing the data stream to complete the activity. At a LUN level, this usually involves some form of locking mechanism to pause all IO while any metadata updates or data redirections are made, after which the IO is resumed.

For small machines and LUNs with minimal IO load this is generally such a quick operation that it has virtually no effect on the application user, and is pretty much transparent. For busy applications, however, data can be changing at such a massive rate that disrupting that IO stream, even for a few seconds can have a significant impact on performance and user experience. In addition the larger the number of snapshots in the snap tree, the more that performance is often degraded through the management of large numbers of snapshots, copy on write activities, and, of course, lots of locking.

This problem is then multiplied several times over when you want to get consistency across multiple machines, for example when you want to get point-in-time consistency for an entire application stack (Web / App / DB, etc).

So what do we typically do? We reduce the regularity at which we take these snaps in order to minimise the impact, whilst still having to meet the (usually near zero because all data is critical, right?) RPO set by the business.

At SFD8, we had a very well received presentation from INFINIDAT, a storage startup based in Israel and founded by industry legend Moshe Yanai (the guy who brought you EMC Symmetrix / VMAX, and subsequently XIV). Moshe’s “third generation” enterprise class storage system comes with one particular feature with which I was really interested; snapshots! Yes, I know it sounds like a boring “checkbox in an RFP” feature, but when I found out how it worked I was really impressed.

For every single write stripe which goes to disk, a checksum and a timestamp (from a high precision clock) are written. This forms the base on which the snapshot system is built (something they call InfiniSnap™).

If you have a micro-second accurate clock and timestamps on every write, then in order to achieve a snapshot you simply have to pick a date and time! Anything written earlier than this is not included in the current snap, and anything on or after the time is. This means no locking or pausing of IO during a snap, making the entire process a near zero time and a zero impact operation! A volume with or without snapshots, therefore has indistinguishable performance. Wow!

Screen Shot 2015-12-13 at 20.55.19

It sounds so simple it shouldn’t work, but according to INFINIDAT they can easily support up to 100,000 snaps per system, and even this isn’t even a real number. They made it up as it was a double figure percentage bigger than the next closest array on the market. They will also happily support more than this if you ask, they said that they just need to test it first. In addition, each snap group will support up to 25 snaps per second, and they guarantee an RPO of as low as 4 seconds, based on snapshots alone. You can then use point in time replication to create an asynchronous copy on another array if needed. Now that’s granular! 🙂

The one caveat I would add to this is that this does not yet appear to have a fix for ye old faithful crash consistent vs application consistent issue, but it’s a great start. Going back to the application stack “consistency group” concept, in theory, you generally only need to VSS the database VM, and as such it will be much easier and simpler to have a consistent snap across an app stack with minimal overhead. As we move more towards applications using No-SQL databases etc, this will also become less of an issue.

The above was just one of the cool features they covered in their presentation, from which the general consensus was very positive indeed! A couple of weeks ago I was also able to spend a little time with one of INFINIDAT’s customers who just so happened to be attending the same UKVMUG event. Their impressions in terms of the quality of the array build (with a claimed 99.99999% availability!), the management interface, general performance during initial testing, the compelling pricing, and of course, their very funky matrix-like chassis, were all very positive too.

If you want to see the INFINIDAT presentation from SFD8, make sure you have your thinking hat on and a large jug of coffee! Their very passionate CTO, Brian Carmody, was a very compelling speaker and was more than happy to get stuck into the detail of how the technology works. I definitely felt that I came away a little smarter having been a part of the audience! He also goes into some fascinating detail about genome sequencing, the concept of cost per genome and it’s likely massive impact on the storage industry and our lives in general! The video is worth a watch for this section alone…

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

Dan FrithINFINIDAT – What exactly is a “Moshe v3.0”?
Enrico Signoretti’s blog Juku.itInfinidat: awesome tech, great execution
Enrico Signoretti writing on El RegHas the next generation of monolithic storage arrived?
Ray LucchesiMobile devices as a cache for cloud data
Vipin V.K. – Infinibox – Enterprise storage solution from Infinidat
GreyBeards on Storage Podcast – Interview with Brian Carmody

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.

Where and why is my data growing?…

I’ve written recently about issues of data gravity and data inertia, and about how important analytics are to managing your data “stockpile”, but one thing I haven’t gone into is the constant challenge of actually understanding your data composition, i.e. what the hell am I actually storing?!

Looking back to my days as a Windows admin maintaining what for the time were some massive, multi-terabyte (ooer – it was 10 years ago to be fair), filers and shared document storage systems; we had little to tell us what the DNA of those file shares was, how much of it was documents and other business-related content, and how much of it was actually people storing their entire MP3 collections and “family photos” on their work shared drives (yes, 100% true!).

Back then our only method of combating these issues was to run TreeSize to see who was using most space, then do windows searches for specific file types and manually clear out the crud; an unenviable task which came across a few surprising finds I won’t go into just now (ooer for the second time)! The problem was that we just didn’t know what we had!

Ten years later I have spoken to customers who are consuming data at very significant rates, but don’t have a grip on where it’s all going…

With that in mind, I was really interested in what the chaps at Qumulo had come up with when they presented at SFD8 recently. As they said at the time, the management of storage is getting easier, but the management of data is getting very much harder! Their primary vision is therefore quite succinctly described as “Build visible data and make storage invisible”.

Their “Data Aware” scale-out NAS solution is based around providing near-realtime analytics on the metadata, and was designed to meet the requirements of the 600 companies and individuals they interviewed before they even came up with their idea!

The product is designed to be software only and subscription-based, though they also provide scale out physical 1u / 4u appliances as well. I guess the main concept there is “have it your way”; there are still plenty of customers out there who want to buy software solution which is pre-qualified and supported on specific hardware (which sounds like an oxymoron but each to their own I say)! Most of Qumulo’s customers today actually buy the appliances.

The coolest thing about their solution is definitely their unique file system (QSFS – Qumulo Scalable File System). It uses a very clever, proprietary method to track changes within the filesystem based on the aggregate of child attributes in the tree (see their SFD8 presentation for more info). As you then don’t need to necessarily walk the entire tree to get an answer to a query (it should be noted this would be one specifically catered for by Qumulo though). It can then present statistics based on those attributes in near-realtime.

Whiteboard Dude approves!

Whiteboard Dude approves!

I would have killed for this level and speed of insight back in my admin days, and frankly I have a few customers right now who would really benefit!

Taking this a step further, the analytics can also provide performance statistics based on file path and type, so for example it could show you where the hotspots are in your filesystem, and which clients are generating them.

Who's using my storage?

Who’s using my storage?

Stuff I would like to see in future versions (though I know they don’t chase the Service Provider market), would be things like the ability to present storage to more than one Active Directory domain, straight forward RBAC (Role Based Access Control) at the management layer, more of the standard data services you see from most vendors (the RFP tick box features). Being able to mix and match the physical appliance types would also be useful as you scale and your requirements change over time, but I guess if you need flexibility, go with the software-only solution.

At a non-feature level, it would be sensible if they could rename their aggregate terminology as I think it just confuses people (aggregates typically mean something else to most storage bods).

Capacity Visualisation

Capacity Visualisation

Overall though I think the Qumulo system is impressive, as are the founder’s credentials. Their CEO/CTO team of Peter Godman and Aaron Passey, with whom we had a good chinwag outside of the SFD8 arena, both played a big part in building the Isilon storage system. As an organisation they already regularly work with customers with over 10 billion files today and up to 4PB of storage.

If their system is capable of handling this kind of scalability having only come out of stealth 8 months ago, they’re definitely one to watch…

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

Dan Frith – Qumulo – Storage for people who care about their data

Scott D. Lowe – Data Awareness Is Increasingly Popular in the Storage Biz

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.

 

Looking Forward to Storage Field Day 8

Storage Field Day

I have been a fan of the Tech Field Day events for some time. They provide a really interesting approach to tech marketing and are a great way of keeping up with the latest developments in the industry, as tech startups and established players alike take to the stage to showcase / discuss (and often get grilled by the delegates about) their shiniest new toys and features.

One of the key services I see the guys at TFD providing (free!) to the community is helping to maintain our knowledge of the bewildering array (pardon the pun) of vendors and solutions that are available out there, in an easy to consume format. It’s important to keep up with current trends and releases in the storage arena, even if you only have vendor X or Y in your current environment. If only so that when your IT Director says to you he wants to go out and buy vendor Z you can have a sensible, fact based conversation as to why or why not to consider them (instead of the obvious knee jerk reaction which they will potentially be expecting!). In my case I’m just a massive geek who loves talking / learning / reading / writing about tech, so keeping up definitely isn’t a chore for me! 🙂

So with that in mind, I am very honoured and excited to have been invited to attend Storage Field Day 8 from the 21st to 23rd October this year. Thank you very much to Stephen Foskett (@SFoskett) and Claire Chaplais (@cchaplais) for the awesome opportunity!

I would consider myself an IT generalist with a penchant for virtualisation and storage. The thing that has really drawn my interest to the storage field has been the fact that it is one of the fastest moving parts of the industry today, with the most innovation and potential disruption from startups.

You don’t have to be an established player to be successful any more. The cost of entry when basing your solutions on Intel chips and white box chassis with a layer of cleverly written software is a heck of a lot cheaper than the custom hardware driven solutions of the past! As many companies have a wide selection of storage silos across their estates, it is also not so difficult to encourage them to try out your new solution to initially replace a single silo either. Lastly lets be honest, we all like an underdog, and there are quite a few underdogs nipping at the bellies of the 880lb storage gorillas as we speak!

Morpheus doesnt like high margin storage

For the past three years I have been working as a Solution Architect at Claranet, an independent pan-European managed services provider, designing hosting solutions for the mid-market; an interesting and challenging sector where aspirations sometimes exceed budgets. That said, I will try not to repeat the traditional service provider mantra of “Can I securely multi-tenant it?” and “Do you provide an Opex commercial model?” too much…

I am really looking forward to enabling my brain sponge and soaking up the vast combined knowledge of the delegates and presenters at the event (some of whom I listen to regularly on the highly recommended podcasts Greybeards on Storage and In Tech We Trust and all of whom are known for producing awesome community content), so be sure to check them out and follow them on twitter!

The list of vendors at SFD8 is extensive too… with some new names who only came out of stealth in the past year along with the more familiar ones, it should be a fascinating week!

SFD8 Vendors

You can join the live stream during the event, and recordings of all sessions are available after, all of which you can find here:
http://techfieldday.com/event/sfd8/

PS: Being half Saffa, half Scot I was a bit concerned I might miss some of the RWC 2015 action by being in the States during the semi final stage, but after spending this Saturday sitting in the stands during the (now infamous) SA vs Japan game, I’m sadly less concerned about that possible outcome now!

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