USP-V does SATA

So the rumours (here and here) are true. Here's the announcement to prove it. HDS are going to support 750GB SATA II drives in the USP.

This is an interesting position HDS are taking as thin provisioning will be able to take use of the enhanced drive capacity making the USP-V even more efficient than the DMX-4 with SATA drives.

However I do wonder whether HDS have been pushed into supporting SATA on the USP-V. I was under the impression that thin provisioning on external drives (the standard HDS line - use External SATA storage rather than configuring it within the USP itself) wasn't going to be available in the initial release. Perhaps HDS had to support SATA in order to get best usage out of the thin provisioning option and to answer customer complaints about using thin provisioning with expensive storage.

What I'd like to see next is how HDS will now position internal versus external storage. At what point do externally connected SATA drives become more cost effective than internal ones? This announcement seems to muddy the waters from that perspective.

I imagine we will get an announcement from Hu explaining how logical it is and how it is all part of the ongoing strategy....

SPC

According to Wikipedia, lightning can travel at a speed of 100,000 MPH, however I think storage vendors are even faster than lightning when it comes to highlighting or dissing the competition.

Mere microseconds after reading Claus Mikkelsen's blog on the USP-V SPC figures, there are posts from BarryW and BarryB, doing the highlighting and dissing respectively (I almost wrote respectfully there; that would have been a funny typo). BarryB must have no real work to do other than to write his blog, looking at the size of the posts he does!

Anyway. I'm not going to comment on the results because the others have done that enough already and I don't think the details are that relevant. I think what's more relevant is the stance EMC are taking in not providing figures for customers on the performance of their equipment. I can't decide whether its a case of arrogance and therefore a feeling they don't need to provide details because as BarryB says, the customer will buy anyway, or is it because the DMX will not match up to the performance of its competitors. I think it is a mixture of both.

EMC aren't an array vendor any more and haven't been for a long time. OK, it is the product they're most remembered for historically, but their reach is now so wide and deep I think Symmetrix isn't the focus of a lot of their attentions. If it was, DMX4 would not just scale by the GB, it would have more connectivity, more cache and EMC would have been the *leader* in the implementation of technology like thin provisioning, not the also ran.

On reflection, I think EMC should provide SPC figures. If DMX is better than the others and is "Simply the Best" prove it; bragging starts to sound hollow after a while.

DMX-4 Green or not?

After the recent EMC announcements on DMX-4, I promised I would look at the question of whether the new DMX-4 is really as green as it claims to be. I did some research and the results are quite interesting.



Firstly we need to set the boundaries. One of the hardest part of comparing hardware from different manufacturers is that they are intrinsically different (if they were too similar, the lawyers would be involved) and that makes it difficult to come up with a fair comparison. So, I've divided the comparisons into controller and disk array cabinets. Even this is difficult. The DMX has a central controller cabinet which contains only batteries, power supplies, interface boards and so on. The USP however uses half of the central controller for disks. The DMX has 240 drives per cabinet, however the USP has 256 disks per cabinet. This all needs to be taken into consideration when performing calculations.



Second, I want to explain my sources. I've tried to avoid the marketing figures for two reasons; firstly they usually refer to a fully configured system and secondly they don't provide enough detail in order to break down power usage by cabinet and by component. This level of detail is necessary for a more exact comparison. So, for the USP and USP-V, I'm using HDS's own power calculation spreadsheet. This is quite detailed, and allows each component in a configuration to be specified in the power calculation. For EMC, I'm using the DMX-3 Physical Planning Guide. I can't find a DMX-4 Planning Guide yet, however the figures on the EMC website for DMX-4 are almost identical to those for DMX-3 and it's as close as I can get.



DMX-3/4



The DMX figures are quite simple; the controller cabinet (fully loaded) takes 6.4KVA and a disk cabinet 6.1KVA. A fully configured controller cabinet has 24 controller slots, up to 8 global memory directors and 16 back and front-end director (FED) cards. A typical configuration would have eight 8-port FED cards and 8 BED cards connecting to all 4 disk quadrants. EMC quote the disk cabinet figures based on 10K drives. Looking at Seagate's website and standard 10K 300GB FC drives, each requires 18W of power in "normal" operation, so 240 drives requires 4.32KVA. The difference between this figure and the EMC value will cover when drives are being driven harder and the power supplies and other components which need powering within a disk cabinet. We can therefore work on an assumption of 25.4W per drive on average.

Now the figures for the controller cabinet are interesting. Remember EMC have no drives in the controller cabinet so all the power is for controllers, charging batteries and cache. So all that 6.4KVA is dedicated to keeping the box running.

USP

The HDS power calculator spreadsheet is quite detailed. It allows specific details of cache, BEDS, FEDs and a mix of 73/144/300GB array groups. A full USP1100 configuration has 1152 drives, 6 FEDs, 4 BEDs and 256GB of cache. This full configuration draws 38.93KVA (slightly more than the quoted figure on the HDS website. Dropping off 64 array groups (an array cabinet) reduces the power requirement to 31.50 KVA or 7.43KVA for the whole cabinet. This means the controller cabinet draws 9.21KVA and in fact the spreadsheet shows that a full configuration minus disks draws 5.4KVA. The controller cabinet has up to 128 drives in it, which should translate to about 3.7KVA; this is consistent with the 9.21KVA drawn by a full controller cabinet. The 7.43KVA in a cabinet translates to 29W per drive, making the HDS "per drive" cost more expensive.

This is a lot of data, probably not well presented but it shows a number of things;

1. There's an inescapable power draw per drive which can't be avoided; this equates to about 20W per drive.
2. The controller frame needs about 6KVA and this varies only slightly depending on the number of controllers and cache.
3. The HDS controller is slightly more efficient than the EMC.
4. The HDS disk array is slightly less efficient than the EMC.

Neither vendor can really claim their product to be "green". EMC are playing the green card by using their higher density drives. There's no doubting that this does compute to a better capacity to power ratio, however these green power savings come at a cost; SATA drives are not fibre channel and not designed for 24/7 workloads. Whilst these drives provide increased capacity, they don't provide the same level of performance and DMX systems are priced at a premium so you want to get the best bang for your buck. However, if EMC were to price a SATA-based DMX competitively, then the model is compelling, but surely that would take business away from Clariion. What's more likely to happen is customers choosing to put some SATA drives into an array and therefore see only modest incremental power savings.

So what's the future? Well, 2.5" drives currently offer up to 146GB capacity at 10K and only half the power demands, which also translates into cooling savings. Is anyone using these in building arrays? Hybrid drives with more cache should allow drives to be spun down periodically, also saving power. Either way, these sorts of features shoudn't come at the cost of the levels of performance and availability we see today.

One final note of interest...HDS are quoting figures for the USP-V. These show a 10% saving over the standard USP, despite the performance improvements...

New Product Announcement,,,

There's another new product out this week from HP - the XP24000... It seems to have some similarities to another product launch, 224 ports, thin provisioning, partitioning... :-)

USP-V...and another thing

I hate it when I write a post then think of other things afterwards. One more USP-V thought (I'm sure there will be more). One of the drawbacks of the current hardware with virtualisation is the effort to remove/upgrade the USP. Was there anything in the announcements on Monday to cater for this? I was hoping HDS would announce USP "clustering". Although they don't think it is necessary from a resiliency perspective, it certainly is if you want to upgrade and haven't done a 1 for 1 passthrough on LUNs (i.e. presented "big" LUNs to the array and then carved them up in the USP).

So HDS, did you do it?

Oh, and another one...for customers who've just purchased a standard USP, will there be a field upgrade to USP-V?

USP-V - bit of a let down?

It seems from the posts seen so far on the blogosphere that the USP release is causing a bit of a stir (10 points for stating the obvious I think). So, here’s my take on the announcements so far.

First of all, it’s called USP-V – presumably because of the “Massive 500-Percent Increase in Virtualized Storage Port Performance for External Storage”. I'm not sure what that means - possibly more on that later.

As previously pointed out, the USP-V doesn’t increase the number of disks it supports. It stays at 1152 and disappointingly the largest drive size is still 300GB and only 146GB for 15K drives. I assume HDS intends to suggest that customers should be using virtualisation to connect to lower cost, higher capacity storage. That’s a laudible suggestion and only works if the Universal Volume Manager licence is attractive to make it work. In my experience this is an expensive feature and unless you’re virtualising a shed-load of storage, then it probably isn’t cost effective.

There have been some capacity increases; the number of logical LUNs increases 4-fold. I think this has been needed for some time, especially if using virtualisation. 332TB with 16384 virtual LUNs meant an average of 20GB per LUN, obviously now it is only 4GB. Incidentally, the HDS website originally showed the wrong internal capacity here: http://www.hds.com/products/storage-systems/capacity.html, showing the USP-V figures the same as the base USP100. It’s now been corrected!

Front-end ports and back-end directors have been increased. For fibre-channel the increase is from 192 to 224 ports (presumably 12 to 14 boards) and back-end directors increase from a maximum of 4 to 8. I’m not sure why this is if the number of supportable drives hasn’t been increased (do HDS think 4 was insufficient or will be see a USP-V MKII with support for more drives?). Although these are theoretical maxima, the figures need to be taken with a pinch of salt. For example, the front-end ports are 16-port cards in the USP and there are 6 slots. This provides 96 ports, the next 96 are provided by stealing back-end directors (this is similar to DMX-3 – 64 ports maximum which can be increased to 80 by removing disk director cards). Surprisingly, throughput hasn’t been increased. Control bandwidth has, but not cache bandwidth. Does the control bandwidth increase provide the 500% increase in virtualisation throughput for external storage?

What about the “good stuff”? So, far, all I can see is Dynamic (thin) Provisioning and some enhancements to virtual partitions. The thin provisioning claims to create virtual LUNs and spread data across a wide number of array groups. I suspect this is simply an extension of the existing copy-on-write technology, which if it is, makes it hardly revolutionary.

I’d say the USP-V is an incremental change to the existing USP and not quite worthy of the fanfare and secrecy of the last 6 months. I’d like to see some more technical detail (HDS feel free to forward me whatever you like to contradict my opinion).

One other thought. I don’t think the DMX-3 was any less or more radical when it was released....