Stephen Foskett, Pack Rat

Around NX4 integration what exactly is needed here? Does everything need to be mashed together or can it be integrated at the management layer?

Will or should a customer care if I select “Replicate this volume” from a properties list and Celerra Replicator does it or MirrorView does it?

As you know, translation layers and the time it takes to do them can differ significantly and depend heavily on storage-system architecture. If you know how to read benchmarks, you can get some indication of what the virtualization latencies are. Storage performance benchmarks define 100% workload as the amount of throughput (I/Os or streaming) at some reasonable low latency level. You should look at the whole performance curve to understand the latencies given for various throughput measurements. For instance, Netapp's SPC data tends to indicate competitive latency levels at low to mid workloads and much higher latency levels at high workloads. Industry insiders suspect EMC doesn't publish SPC benchmarks because they would indicate a relatively sad tale of latency – despite their claims about benchmark fairness and the necessity of mixed workload benchmarks.

I would bet that integrated management would be enough for most people, since that's what they interact with. I can imagine that, if replicating NFS uses totally different protocols than replicating a block volume, they might care about the underlying technology. But if you can make it “just work”, then why would they care about it unless they were techies arguing over whose is bigger?

I tend to be a realist. Whatever works (really works, not just sounds like it will) is always the best solution. And this is the point I was trying to make here: It doesn't really matter how unified you are or how emulated you are – it only matters if it's the right tool to get done what you need.

Yes again, Marc! What's the takeaway message? Regardless of the rightness or wrongness of a certain approach to solve a problem, the proof is in the pudding. Does it work? Does it continue to work as you use it?

I've seen some really BLAZING performance from EMC's CX series, for example. And I've also seen it suck. It depends on how you configure it and what you are looking for!

Hi Steve — great post, as usual. There's a good reason why you're on my blog rail!

If you don't mind, a few clarifying statements?

You are quite correct that most FC and iSCSI arrays compose physical disks and allow users to slice them up into logical chunks. However, this can be done preserving the physical nature of the drives, if desired — for example, putting data on outer tracks to get more performance, or laying things out sequentially if needed, or building certain kinds of wide stripes.

My issue with NetApp and similar emulated approaches is that you lose this capability. The array decides how to lay out the data, and not a skilled user. In some cases, this is not a big deal — especially when the workloads are not demanding. But, when workloads are demanding, you've taken away an important tool from the storage admin's bag of tricks. And this tends to show up in demanding FC environments.

Put differently, sometimes it's OK to have a file system abstraction layer between you and your disks, and sometimes it's not.

My second comment is that I disagree as to where this might be important. You state it's all about overselling low-end kit. I tend to think it's about having the right tools for the job at hand. Part of the problem is that statements like “Exchange ran OK” are meaningless without context, given the incredibly wide range of how people actually use these applications. I've seen people run Exchange inside a virtual machine from a desktop. It worked great — for what they were doing!

Finally, this argument extends well outside of the low-end, and into healthy-sized configurations of both NetApp's FAS products, as well as EMC's Celerra / CX product line, where perhaps the differences would be more noticeable.

Thanks again for a thoughtful post!

– Chuck

I see your point now, Chuck – true, some arrays give lots of manual control over layout (like the EMC CX line) and others are totally automated (for example, EqualLogic). I'm not sure which is truly “better” – it depends on the aims of whoever is managing it, I suppose! This is a great topic for a future post!

I certainly agree that this is important at all levels, but the discussion I linked to was totally focused on the specific case of the NX/AX and lower-end NetApp gear, at least to my eyes. If we open up discussion to the whole of enterprise storage, I bet the discussion would be similar, though the differences might indeed be greater.

Thanks for reading and posting!

Industry Insiders need to stop whining about it and move on, it is now assured to never change. this year we saw that SPC is a marketing con job from an anti-EMC organisation. They confirmed that when they accepted bullshit numbers about EMC gear from a competitor.

Anyone else benchmarked the other guys tin yet?

I'll make sure we never support that piece of shit or that organisation.

As for translation layers and so on, not my issue on CX. At it's base the CX is cache and mathematical lookup. No file systems, not file systems or mutant duck/snake/spider animals. No worrying about where the metadata is or how it's protected or what happens if that metadata goes away. You give me the address you wrote the data to I'll perform a calculation then tell you the disk and sector the data is sitting on as well as point to the data integrity bits are right next to it.

Elegant, fast and not prone to bugs.

Showing a little teeth? I agree that the SPC should not have published Netapp's Clariion numbers. That was an unfortunate stunt.

SPC brings down the red mist. I had no problem with it until they showed they had a problem with us.

I'm Irish. I'll hate it forever.

Around NX4 integration what exactly is needed here? Does everything need to be mashed together or can it be integrated at the management layer?

Will or should a customer care if I select “Replicate this volume” from a properties list and Celerra Replicator does it or MirrorView does it depending on if it's an FC attach or NAS volume?

As you know, translation layers and the time it takes to do them can differ significantly and depend heavily on storage-system architecture. If you know how to read benchmarks, you can get some indication of what the virtualization latencies are. Storage performance benchmarks define 100% workload as the amount of throughput (I/Os or streaming) at some reasonable low latency level. You should look at the whole performance curve to understand the latencies given for various throughput measurements. For instance, Netapp's SPC data tends to indicate competitive latency levels at low to mid workloads and much higher latency levels at high workloads. Industry insiders suspect EMC doesn't publish SPC benchmarks because they would indicate a relatively sad tale of latency – despite their claims about benchmark fairness and the necessity of mixed workload benchmarks.

I would bet that integrated management would be enough for most people, since that's what they interact with. I can imagine that, if replicating NFS uses totally different protocols than replicating a block volume, they might care about the underlying technology. But if you can make it “just work”, then why would they care about it unless they were techies arguing over whose is bigger?

I tend to be a realist. Whatever works (really works, not just sounds like it will) is always the best solution. And this is the point I was trying to make here: It doesn't really matter how unified you are or how emulated you are – it only matters if it's the right tool to get done what you need.

Yes again, Marc! What's the takeaway message? Regardless of the rightness or wrongness of a certain approach to solve a problem, the proof is in the pudding. Does it work? Does it continue to work as you use it?

I've seen some really BLAZING performance from EMC's CX series, for example. And I've also seen it suck. It depends on how you configure it and what you are looking for!

Hi Steve — great post, as usual. There's a good reason why you're on my blog rail!

If you don't mind, a few clarifying statements?

You are quite correct that most FC and iSCSI arrays compose physical disks and allow users to slice them up into logical chunks. However, this can be done preserving the physical nature of the drives, if desired — for example, putting data on outer tracks to get more performance, or laying things out sequentially if needed, or building certain kinds of wide stripes.

My issue with NetApp and similar emulated approaches is that you lose this capability. The array decides how to lay out the data, and not a skilled user. In some cases, this is not a big deal — especially when the workloads are not demanding. But, when workloads are demanding, you've taken away an important tool from the storage admin's bag of tricks. And this tends to show up in demanding FC environments.

Put differently, sometimes it's OK to have a file system abstraction layer between you and your disks, and sometimes it's not.

My second comment is that I disagree as to where this might be important. You state it's all about overselling low-end kit. I tend to think it's about having the right tools for the job at hand. Part of the problem is that statements like “Exchange ran OK” are meaningless without context, given the incredibly wide range of how people actually use these applications. I've seen people run Exchange inside a virtual machine from a desktop. It worked great — for what they were doing!

Finally, this argument extends well outside of the low-end, and into healthy-sized configurations of both NetApp's FAS products, as well as EMC's Celerra / CX product line, where perhaps the differences would be more noticeable.

Thanks again for a thoughtful post!

– Chuck

I see your point now, Chuck – true, some arrays give lots of manual control over layout (like the EMC CX line) and others are totally automated (for example, EqualLogic). I'm not sure which is truly “better” – it depends on the aims of whoever is managing it, I suppose! This is a great topic for a future post!

I certainly agree that this is important at all levels, but the discussion I linked to was totally focused on the specific case of the NX/AX and lower-end NetApp gear, at least to my eyes. If we open up discussion to the whole of enterprise storage, I bet the discussion would be similar, though the differences might indeed be greater.

Thanks for reading and posting!

Industry Insiders need to stop whining about it and move on, it is now assured to never change. This year we saw that SPC is a marketing con job from an anti-EMC organisation. They confirmed that when they accepted bullshit numbers about EMC gear from a competitor.

Anyone else benchmarked the other guys tin yet?

I'll make sure we never support that piece of shit or that organisation.

As for translation layers and so on, not my issue on CX. At it's base the CX is cache and mathematical lookup. No file systems, not file systems or mutant duck/snake/spider animals. No worrying about where the metadata is or how it's protected or what happens if that metadata goes away. You give me the address you wrote the data to I'll perform a calculation then tell you the disk and sector the data is sitting on as well as point to the data integrity bits are right next to it.

Elegant, fast and not prone to bugs.

Showing a little teeth? I agree that the SPC should not have published Netapp's Clariion numbers. That was an unfortunate stunt.

SPC brings down the red mist. I had no problem with it until they showed they had a problem with us.

I'm Irish. I'll hate it forever.

Nice article Stephen. Disclaimer – I am a NetApp employee and a former employee of EMC. Been there, done that.

Chuck makes an interesting point below – the ability for an admin to choose where on a set of spindles his data will reside is a nice thing to have for the most demanding workloads. But these workloads are comparatively few. In fact, my personal experience with installed DMX and CLARiiON arrays bears out this one bit of real world experience –

If you are going to need dedicated IO's that the outer tracks of a set of spindles will give you, then *most likely* the workload is high enough that the inner tracks will go unused because you cannot afford to throw any other application workload at the spindles.

Hence the cost is very high – but sometimes you do run into this need. But as a rule, it is not needed for the vast majority of applications… just a very few.

Any other conversation is pure FUD. Been there.

I will probably blog on the Low Art of FUD soon. Why ?? Because the IT community needs to know this – FUD wastes *your* time and energy – not mine. All vendors have a database of some sort full of razor sharp answers to any and all FUD. Especially the kind that Chuck tosses around. Vendor Olympics is about the customer tiring himself out – not exercising the vendor.

We do this for a living folks!

Cheers !

Nice article Stephen. Disclaimer – I am a NetApp employee and a former employee of EMC. Been there, done that.

Chuck makes an interesting point below – the ability for an admin to choose where on a set of spindles his data will reside is a nice thing to have for the most demanding workloads. But these workloads are comparatively few. In fact, my personal experience with installed DMX and CLARiiON arrays bears out this one bit of real world experience –

If you are going to need dedicated IO's that the outer tracks of a set of spindles will give you, then *most likely* the workload is high enough that the inner tracks will go unused because you cannot afford to throw any other application workload at the spindles.

Hence the cost is very high – but sometimes you do run into this need. But as a rule, it is not needed for the vast majority of applications… just a very few.

Any other conversation is pure FUD. Been there.

I will probably blog on the Low Art of FUD soon. Why ?? Because the IT community needs to know this – FUD wastes *your* time and energy – not mine. All vendors have a database of some sort full of razor sharp answers to any and all FUD. Especially the kind that Chuck tosses around. Vendor Olympics is about the customer tiring himself out – not exercising the vendor.

We do this for a living folks!

Cheers !

[...] Foskett, a storage consultant, posts what I think is an excellent overview of the issues. He cuts through the marketing spin and asks the right questions. His coverage of the topic is so [...]