NOTE: This post has been renamed from "Energy matters, apparently!"
In a response to my last post, Barry, of the Burke variety (seeing as we are now “blessed” with two Barry’s), pointed to an energy related post that talked about the recent Hitachi power savings announcement. The post was written by Dick Sullivan, a fellow drone of Barry’s at the Energy Matters Corporation.
Thanks Barry, but it took me 3 or 4 minutes to read the post and those are 3 or 4 minutes of my life that I would like back. But since Ive already lived more minutes than can be addressed by a DMX-4, and hope to live more than can be addressed by a USP-V I wont quibble too much ;-)
Here are a couple of comments on Dicks post –
Blah blah blah....
Dick starts out by pooh poohing Hitachi’s recent AMS/WMS power saving RAID Group announcement, basically saying its nice of Hitachi to do their part, but of course EMC has been doing its part for much longer…
He then seems to suggest that its not really worth all the effort on midrange storage. After all, midrange storage doesn’t really suck that much energy in the first place so why bother!?!? Oh and of course Hitachi are not keeping the disks turned off all of the time!?!?
He then moves on to moan that as we start to crank up the utilisation of these power saving disk groups we will gradually save less and less energy. Well thanks for that little gem. Same tends to go for performance – the more space on a disk you use, the more performance tends to tail off. That doesn’t mean we throw in the performance towel from the start with the attitude that it will eventually degrade as utilisation increases. Dick seems to take this attitude over power saving disk groups though.
He then has a moan about this being offered initially only as a service, and hence billable – I quote “If customers need training to use a feature, it has to make you wonder about some of the gotchas that tend not to be covered in a press release”. Indicating that if customers need training then it must be riddled with gotchas!?!? EMC never train any of its customers or offer any features that can only be implemented as a service???? Hmmmmmm…… kettle, pot……
He then moves onto the reliability of drives that are spun up and down frequently – yes that old chestnut. OK, so I'll side with him to a point on this one. I still have to be won over on this one. Although since reading the HDS press release I have done a little (soon to be more than a little) research on modern disk drives and how they cope with this kind of treatment and Im starting to wonder if this will turn out to be such an issue after all?
While I personally do have niggling concerns over this, I think Dick is laying the FUD on a little thickly with comments such as - when I spin the drives back up, “Will the data still be there? Will the application recognise it?”. As if he has never turned his laptop on and off, or powered down a CLARiiON in his life (may be he hasn’t).
It just seems too easy to bring this up in response to the Hitachi announcement, and a lot of people have, including me. But I have to wonder how much these folks (myself and Dick included) actually know about the workings and tolerances of disk drives, especially those installed in storage arrays? Im willing to bet not as much as the people that matter at Hitachi. Anybody out there think that Hitachi are about to stake their reputation on something they are not sure about? Don't be soft!
From a high level view, I’m a big believer that my laptop is to a disk drive, what the summit of Mount Everest is to a sick person needing oxygen. While on the other hand a storage array is to a disk drive what an Intensive Care Unit is to s sick person needing oxygen. And I’ve never lost data from my laptop never mind and storage array, so I’m probably not going to lose too much sleep over this one.
I think a good place to start with this technology will be disk groups dedicated to staging backups before being spooled off to tape. If it proves itself there, lets move it further into the Data Centre.
Dick then drops in a fantastic quote – Apparently one (only one??) unnamed VP of an unnamed “major financial company” is quoted as saying the USP is “ridiculous”. Wow quite some quote. Oh, and this unnamed VP from the unnamed company apparently has Hitachi gear. Although its not clear whether this is a USP or a flat screen TV. Zzzzzzzzz
Then ……. yes there’s more….. he has a pop at the fact Hitachi didn’t mention performance in this announcement. Fair enough, but he then goes on to state that EMC does all of its power saving magic without sacrificing performance – again I quote - “One of the key design points for EMC is to do all of this power savings without sacrificing performance”. Wow, so apparently you wont see a performance impact if you move some of your data off of FC and on to the newly supported SATAII drives that play such a huge role in the energy efficiency of the DMX-4 – now that’s what I call magic!
The differences that dont exist....
From that point on, right up to the very end of the post Dick uses the EMC CLARiiON to contrast the EMC and Hitachi approaches to energy efficiency. For the record, that is from line 76 to line 117 on his post. This is 41 lines, which according to my math is just over a third or just under half of the entire post, depending on how you see it. Why am I mentioning this? Because in my opinion he may as well have left this out because there is little if ANY contrasting done!!!
Don’t believe me, read on…….
The technologies Dick calls on to highlight the contrasts include the following –
- Mix and match drive types within the same system (size, RPM, interface type..)
- Data movement/migration between drive types
- Waffle about SATA being more energy efficient than FC
- Online LU/RAID Group expansion
Not exactly the longest list in the world and not much, if anything, to diff erentiate EMC from the rest of the crowd. Seriously, doesn’t everybody already do this?
I won’t pretend to know as much about midrange stuff as I do about enterprise (and I don’t even know that much about enterprise ;-) but I’ve done all of those things with AMS storage. So where is the contrast?
While Im here I think I’ll also pick up on a couple of other points Dick makes while making these contrasts that don’t appear to exist.
This one is a cracker - While talking about Meta-LUN expansion Dick asserts that you “.. don’t need to have any unused capacity spinning when you place the system on the floor” because “.. when you need it you can add it or expand it without disruption”. Ooooops!! That blatantly ranks as one of those ‘bares absolutely no resemblance to reality’ statements that some folk would have us believe come exclusively from the mouths of Hitachi executives.
So…. shipped many CLARiiONs or Symms with ZERO free capacity recently?? Oh and with the AMS you can now ship that spare capacity, that your customers will demand, but leave it spun down until its needed :-D
Dick also refers to EMC’s Virtual LUN technology as “unique”. Im interested in what makes it unique? Of course Im having a pop here, but actually in all seriousness if it is actually different enough from the rest of the crowd to be referred to as “unique” Im really interested to find out exactly how? Surely we don’t have an EMCer using words like “unique” when they actually mean “ever so slightly different when you examine the minute”.
And I promise this is the last bone I will pick…… but he also states this Virtual LUN technology enables the “….migration of data between LUNs in the array with no application impact….”. I’m interested in how the “no application impact” bit is handled?
Is this handled the same way as others handle it, by only allowing the migration to take place under certain load conditions etc? Otherwise if the source disks are busy handling real I/O and you suddenly start reading every block of a LUN on those same disks so you can copy them to another tier, you are likely to see some performance impact. No?
Yes Dick, energy matters. But so does being fair and honest in your comments.