Enterprise Computing: Has EMC Slipped Zero Block Reclaim Into V-Max?
Posted by Chris Evans on 11 December, 2009
I spent some time today looking at the release notes for Enginuity code 5874.207.166, which presumably is the one that brings the much lauded Fully Automated Storage Tiering (FAST) into general release on V-Max. Just above the FAST paragraph I found the following:
Symmetrix Virtual Provisioning Space Reclamation reduces capacity requirements and total cost of ownership by automatically reclaiming chunks (768 KB track groups) that contain all zeros. This is most effective when used on volumes after thick-to-thin migration or replication.
So, it seems that V-Max now supports features previously only seen on 3Par InServ, HDS USP V and HP XP – that is the ability to reclaim empty “zeros” of data from LUNs – otherwise known as Zero Block Reclaim.
I don’t remember EMC mentioning this little fact as part of their big FAST announcement. In fact, looking back over Barry B’s posts, here’s a link to a post from July in which Barry indicates (quoting again);
I cannot confirm nor deny that VP will support one or more unused space reclamation approaches in the future.
So do EMC just see ongoing space reclamation as a BAU activity, not worthy of an announcement? I’m surprised that this would be the case. Reclamation of “empty” storage is incredibly important when migrating from thick->thin storage environments. Hitachi quote around 40% savings from using ZPR after a migration to thin provisioning on USP V.
Perhaps EMC don’t want us to know that migrating to V-Max can actually reduce the amount of storage in use. After all, its not good for hardware sales, is it?
By the way, EMC, please feel free to comment on this new feature and how easy it is to use. I’d be interested to discover how it is implemented.
This entry was posted on 11 December, 2009 at 1:56 PM and is filed under Enterprise Computing, GestaltIT. Tagged: barry burke, EMC, Enginuity, FAST, V-Max, Zero Block Reclaim, ZPR. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.
Locutus said
Hi Chris,
Chris Evans said
I’m guessing you had more to say than hello?
Chris
Locutus said
Hi Chris, IBM’s SVC announcement in October included a new feature called Zero Detect:
When using Virtual Disk Mirroring to copy from a fully-allocated virtual disk to a space-efficient (thin provisioned) virtual disk, SVC will not copy blocks that are all zeroes
– Disk space is not allocated for unused space or formatted space that is all zeroes
Additionally,when processing a write request, SVC will detect if all zeroes are being written and will not allocate disk space for such requests
– Helps minimize disk space used for space-efficient virtual disks
– Helps avoid space utilization concerns when formatting vdisks
– Supported only on Model CF8 storage engines
So Thin stays Thin.
Chris Evans said
Good point, I should have mentioned SVC too. I was aware, I just forgot.
Chris
Bas Raayman said
Chris, this was indeed part of the new Enginuity. But what is way more important in my opinion, is if they will also provide something like a driver of stack that will actually tell the FS to zero things out and reclaim the space, or if they have gone the 3PAR way and “understand” what the FS does and don’t require any additional installs in the OS.
Chris Evans said
Hmm, didn’t see that mentioned in the release notes. I assume you’re thinking of the Symantec Thin Reclamation API thing? Or perhaps not and thinking they are doing what Data Robotics do?
Chris
Bas Raayman said
Well, basically that would be my question to them. How do they do that, and yes it was exactly what I was thinking of.
Bas Raayman said
Chris,
I just checked and you need Enginuity 5874, and more importantly you need Solutions Enabler 7.1.
With that combination you can use virtual provisioning space reclamation, but there are some drawbacks.
First of all, it’s not sticky.
You issue a “symconfigure free tdev type=reclaim” against an entire thin device or use start and end cylinders and off you go. Problem is that you do this once, but after it finishes the reclaim process it won’t check again. If you have something like a thin pool that you use under vSphere for development machines it would be likely that you will see lot’s of changes on your disks, and to make good use of it you will probably want to run it more frequently.
Secondly, I can only run it against cylinders or thin devices. It would be great for me if I could run it against entire thin pools. Now I need to manually go through all disks or script my process, and with the increasing number of thin devices this is going to cost me more and more time.
What is good is that I don’t need an agent or a piece of software that will tell my array to punch holes, but it’s just not sticky so it’s a manual job.
Last point is that you need at least one thin extent, that means one consecutive part of your disk that has zeroes. Standard thin extent size is 12 tracks or 768KB. If part of the extent has data on it, it won’t be reclaimed.
Hope that helps,
Bas
Chris Evans said
Thanks Bas
It’s pretty much like the HDS implementation – although that won’t work with replication (local or remote) in place.
Frank Bohnsack said
As far as I understand it, EMC will implement a functionality into the storage array to understand the FS functionality and thus be able to identify used and unused blocks on a FS level. So zeroing of unused blocks will be as unnecessary as installation of a software component on the server.
Frank
Chris Evans said
Frank,
That’s how Drobo do it. However it’s tricky to make that work when people have used LVMs to combine individual LUNs together. I suspect there will be lots of caveats and restrictions.
Chris
Frank Bohnsack said
Hi Chris,
yes that’s right, there will be problems when LVMs are used or VMware with VMFS, or … And impressive as it will be that the system will be able to understand Windows, Linux, Solaris, etc. FS it will still be a proprietary solution. I would prefer the extension of the SCSI protocol with commands to tell the storage array that the blocks occupied by deleted files can be released and given back into the free storage pool.
Frank
Enrico Signoretti said
Chris,
Compellent has thin import feature too: it doesn’t writes zeros when you import volumes from other storage arrays.
The feature is very efficient also when you write empty files/blocks ( i.e.: Oracle datafiles).
In these days i see a little bit of negativity on EMC,
ciao,
Enrico
Chris Evans said
Enrico, thanks. Seems more people are doing this than I thought! Still haven’t had chance to get hands-on with Compellent (despite asking).
Chris
Enrico Signoretti said
Compellent has a very good product but their marketing ability doesn’t seem to on par.
Liem Nguyen said
Hi Chris, Enrico, Compellent actually announced Thin Import with Storage Center Release 4.0 in 2008, and along with it an integrated utility called Free Space Recovery, which reclaims whitespace in Windows environments. (If you’re interested, the announcement is here: http://www.compellent.com/News-and-Events/Press-Releases/2008/Storage-Center4_080219.aspx
And, yes, I am working on getting Chris a test unit!
the storage anarchist said
The Enginuity code release you refer to has not yet been formally announced. This week was all about FAST…
Chris Evans said
Ah, sorry about that. I checked the release note document (dated 18th November) and it was tagged with confidentiality of public. I’m sure I haven’t stolen your thunder….
Chris
Paul P said
The bigger picture IMO:
Is that this is not an important event if you you are so late to the party, I mean, why advertise you came last…? Put it in the draw and when the next customer says they want/need this feature, EMC can pull it out and say they have that tick box as well – “now that you mention it, Mr Customer, yes we have that…”
But you also need to view this in relation to EMC’s own perceived value of some of these more modern technologies (i.e. specifically those brought to market by others) – in this case, Chuck’s own comments on a related topic, thin provisioning, summarises, I believe, EMC’s position:
“I think thin provisioning is not-a-good-thing at a philisophical level. It has a role, but I’d recommend using it very carefully, if at all.”
like many technologies other develop – dont believe thin provisioning is useful and one reason, I believe they use a
things
XIV said
Chris,
Just to beat a dead horse….IBM XIV incorporates this ability as well. I would say at this point not having the ability is something to talk about apposed to having it, which all enterprise class arrays should have.
http://www-03.ibm.com/systems/storage/news/press/20091110.html
the storage anarchist said
Now that we’ve formally announced the rest of the functionality included in the Enginuity 5874 update that delivered FAST v1 for V-Max, I’ll be happy to discuss Zero Page Reclaim.
Perhaps best to start with my blog post on the subject: http://bit.ly/784kuT