Migrating a LUN

Question

I'm looking to migrate an existing 250 GB LUN, comprised of ATA disks to a 450 GB LUN, also comprised of ATA disks. I looked at some articles in Powerlink, and it seems like a pretty easy, pretty straightforward process. Any big "gotcha's" I need to watch out for? I believe I read that once the migration is completed, that the NEW LUN will assume the WWN of the older LUN, and the older LUN will be destroyed. Should I assume this to also mean that the new 450 GB LUN will automatically be added to the Host server that the older 250 GB LUN resided on? What about shares? Do the shares and permissions currently in place also get migrated? I also recall reading something that stated that this whole migration process could be done during business hours and would be invisible to the end users. Is this true? I'm just trying to make sure that migrating from a 250 GB LUN to a 450 GB LUN will be as easy as I've read that it'll be.

Thank you in advance

RRR · Accepted Answer

The new 450GB LUN will take the old LUN's identity. The host won't even know anything happaned.
BUT: the host's OS needs to be capable of handling a suddenly larger LUN.

If your host is Windows 2k3 or something and your 250GB LUN is a basic disk, extending the partition afterwards is an online action. If your host is ESX for example, you need to consider that VMFS cannot be extended on the same LUN and you need to create extends ... or something... I'm not a VMware guru.

About shares: whatever is on the LUN, cannot be read by the Clariion, so shares and everything will stay in place.... no worries there

So yes: migrating can be done online

There is a speed setting: low, medium, high and ASAP. ASAP moves really fast, but has an impact on your environment, the other 3 settings are somewhat slower (high is something like 10GB/hour and the other 2 are even slower). There is a document out about the performance impact on a variety of migratiuon settings. I'm so bad with names, I forgot the name of this document of course....

RRR · Answer

You are sooo good

RRR · Answer

Maybe I should give it a try. It's like manuals: ieeeeeeeeeeeeee.....

AranH1 · Answer

That hand dandy search bar actually works

AranH1 · Answer

The name of the document that RRR was thinking of is:
The Influence of Priorities on CLARiiON LUN Management Operations - Applied Technology

It is located at:
Support > Technical Documentation and Advisories > Hardware/Platforms Documentation > CLARiiON CX3 UltraScale Series Systems > CLARiiON CX3-80 > White Papers

And yes it can be done during business hours. I have migrated production LUNs during business hours many times. Just be very careful on the migration setting used. ASAP will definitely impact your array, so if there is not an immediate need for the storage I recommend a Medium setting for the migration. But read the white paper, it will explain it all in detail.

Aran

JD44 · Answer

To RRR and Aran H:Thank you both for the quick replies. This is not a VMware box, so should be pretty smooth. Thanks again for all the help!-Jonathan

AranH1 · Answer

I am ashamed to admit I actually have to read the manual sometimes ... I know I just lost geek points, but it is true....

RRR · Answer

LOL

RRR · Answer

Please mark correct and helpful answers in this thread. It helps future readers to identify the good posts.

AranH1 · Answer

JD44,The site can be a little flaky sometimes. No need to apologize, even on vacation Rob is still a point fiend What migration setting were you using? The fact that it was taking so long sounds like a Low setting which should have no noticeable impact on performance.Aran

JD44 · Answer

Will do. My inexperience on this site reared its ugly head, as I didn't realize to do this. I just tried marking a "correct" and "helpful" post, and both brought me to an "Unable to display page" window. I'll try it again later.

As an FYI, I canceled the LUN Migration because it only made it to 77% after 3.5 days of running. It was affecting performance on the SP, so I canceled it. I'll try it again this weekend during off hours.

JD44 · Answer

Thanks Aran.Thursday night, when I kicked off the migration, I set it to ASAP, and by 6:00 AM the following morning it was already 51% done. I then lowered the priority from ASAP to medium as I did not want to impact my SAN too much on Friday. Once Friday night rolled around, I turned it back to ASAP. From Friday night until Monday morning, only 26% had been migrated (at the ASAP setting), putting me at 77% when I canceled it. It appears that initially the ASAP setting was clicking along, migrating 51% in a 7 hour time frame. It seemed to really slow down when I changed the priority to Medium (naturally) but never picked back up when I adjusted back to ASAP. That is why I may just may try again this weekend. Over the weekend, I can keep setting at ASAP. So, I'll begin this on ASAP on Friday night, then hopefully by Sunday night it'll be done. The good thing here will be that I won't have to change the priority settings at all (which for some reason seemed to choke the migration I was running last weekend).-Thanks for your help!Jonathan

RRR · Answer

even on vacation Rob is still a point fiend

AranH1 · Answer

Sorry Rob, I couldn't resist

bhtql · Answer

I migrated a 3.5 TB LUN this past weekend from FC to ATA. I have noticed the the progress readings are really inaccurate. It said it had 4 hours to go at 5:00 pm Saturday. at 8:00 am on Sunday it said it had 2 hours to go. 8 hours later it finished. I have seen similar inacurate readings when using SanCopy.

CLARiiON

Migrating a LUN

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