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Help regarding PowerPath Migration Enabler Host Copy
Hello Everyone,
I am pretty new to this PPME thing. I read the white paper on Powerlink, but kind of confussed.
I have 3 Windows host in my environment. For which I am thinking to use PowerPath migration enabler host copy to copy the data from old drive (smaller LUN) to new drive (bigger LUN). I was thinking to use robocopy to copy of data, but I tried in one of my production servers, and to copy of 1 TB of data it took forever.
I read the PowerPath migration enabler host copy document. I had couple of questions
1) I know, I can start the copy at host level, but do I need to install any tool for this, provided that I need to install PPME license on the host.
2) Is it like, it pulls data from one LUN and copies to the new LUN on the same host.
3) What is the best transfer rate for this tool. Taking in to consideration, that I need to copy two 450 GB of LUN in to bigger LUN's of 800GB on the same host and one 1 TB of LUN to copy to 2 TB of LUN on another host. And I have 4 hours of downtime for first and for the other server its 6 hours.
Is their any easy step to follow for host based migration that I might be missing in this tool. Please correct me if I am wrong, do I need to have timefinder clone for this.
Thank You
Rama
Brion2
154 Posts
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September 24th, 2010 07:00
Hi. When upgrading PP for Windows, it will require a host reboot. You don't have to remove the current version (unless there is a hotfix applied). If you have 5.3 SP1, you may directly upgrade to 5.5. The change in bulk data copying behavior from 5.3 SP1 to 5.5 shouldn't be considered a problem. It is a product enhancement. In 5.3 SP1, we paused application I/O temporarily to do bulk data copy operations. The "suspend" time was user configurable depending on the sensitivity of the application. We decided to make an improvement in 5.5 to remove that and perform background copying with application I/O. From a user's point of view, you wouldn't see a difference unless you were doing detailed I/O analysis.
During the bulk data copy (the Sync state) and after the synchronization (the TargetSelected and SourceSelected states), PPME continues to clone all application writes to the devices in the migration to keep them synchronized. Synchronization stops after the migration is committed or aborted.
If you need more information, please let me know.
Thanks, Brion
Brion2
154 Posts
1
September 23rd, 2010 11:00
Hi Rama.
1) 1) Full PowerPath must be installed on the host. PowerPath must also be in control of the LUNs. That is, native MPIO can’t be handling the multipathing.
2) 2) Once the synchronization starts, two operations occur. First, there is the bulk data copy from the source to the target. PPME reads from the source and writes to the target. Second, PowerPath clones all writes to the source and the target.
3) 3) There are too many host factors (e.g. hardware and application) that can impact the rate at which migrations complete. The throttle option is designed to provide flexibility on how fast one or more migrations will take to complete. You have to try it out. You can adjust the migration throttle before or during the migration.
PPME TimeFinder/Clone and Open Replicator require a Symm as the target array. PPME Host Copy support CX, Symm, and qualified non-EMC arrays.
I hope this helps.
Thanks, Brion
hersh1
197 Posts
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September 23rd, 2010 11:00
1) You need to have powerpath licensed for PPME and have PPME installed on the server.
2) Yes copies the data from 1 LUN to the other within the host. It does this by pausing write I/O to the source LUN and copy a chunk of blocks, then allows write I/O to occur. Repeats those steps until it has completed.
3) I would imagine your transfer will depend on a lot of things, connection to your storage array, type of disks you are copying from and to, and settings in PPME. Take a look at this thread for some sample transfer rates I have seen: https://community.emc.com/message/501633#501633. These times we're with an idle host, going between a cx4-960 and cx4-480, Raid5 (4+1) LUNs.
Also you can do this all with no outage to the server since powerpath is handling the cutover.
hersh1
197 Posts
0
September 23rd, 2010 11:00
I must type slower than you.
hersh1
197 Posts
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September 23rd, 2010 11:00
Thanks for clarifying that, had forgotten that was introduced. And it still only does the copy at the interval you provide with the throttle variable? Now just with host I/O occurring at the same time.
Brion2
154 Posts
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September 23rd, 2010 11:00
Just one clarification to your second response. With PowerPath 5.5, an enhancement was made that no longer suspends application I/O to perform bulk data copies.
rama_maddodi
66 Posts
0
September 23rd, 2010 12:00
Hello Everyone,
Thanks Brion and Hersh for the information. Now I get it, I mean clear picture idea about PPME.
Right now, I have Powerpath 5.2 SP 1 onthe server. So I think I might have to update the Powerpath on the box.
I got one more question to ask if I upgrade the Powerpath to 5.3 SP1 or 5.5, and when I start PPME Host copy, so do I need to take downtime for this, as Hersh mentioned that wrtie IO get stoped for some moment of time when its coping the data to new LUN and begins writting the data again, once a bulk of data is wrtten and PP 5.5 doesnt has that problem. It will keep on copying data, to the target LUN even if the host (primary) LUN is getting written. And what about the data which is changed or which is new. Will its be some thing like incremental copy or something.
Please correct, if I am heading wrong way.
kenn2347
542 Posts
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September 24th, 2010 08:00
And it works very well. see my thread i had opened for my experiences
https://community.emc.com/thread/110321?tstart=0
rama_maddodi
66 Posts
0
September 27th, 2010 06:00
Hey thanks, every one for the help. I completed the migration.
Thank You
Rama