acnsys
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Enthusiast

vmotion and databases

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Hi,

I am running sql server 2005 in VMs

My manager doesnt want me to use "vmotion" against db servers during business hours. Is there any particular reasons? I thougt vmotion was totally transparent (though i noticed a ping time out on servers that are vmotion'ed).

Thank you

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demz
Expert
Expert

You can find two interesting links at the end of this post

http://c1tr1xguru.wordpress.com/2008/05/07/virtualized-oracle-database-can-be-migrated-with-zero-dow...

I think if Oracle certified itself VMotion as transparent, your manager has to believe it Smiley Wink

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demz
Expert
Expert

In fact there is no risk, there won't be I/O bottleneck or freeze time (exept a few millisec for 1 or 2 ping), try to convince your manager now...

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demz
Expert
Expert

You can surely find some arguments with that doc :

http://www.vmware.com/pdf/usenix_vmotion.pdf

Hope this will help you.

weinstein5
Immortal
Immortal

It is totally transparent - but you are right you might have a dropped packet or two or an extended ping reponse time but definitely with most network latency/response times -

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BenConrad
Expert
Expert

vMotion is safe.

Worst case should be that for whatever reason the vm is not making enough progress from hostA -> hostB the vMotion will be stopped and the VM continues to run on hostA. As other posters said, you may drop 1-2 pings but 100% of the VM state is intact after vMotion, this includes active sockets, memory contents, CPU state, etc.

I just added up all the vMotions on our US datacenter..... 16,368. If there were issues with vMotion we'd know about it.

Ben

bggb29
Expert
Expert

What is your managers reasons for this.

We vmotion everything including sotrage vmotion during working hours.

Do you run DRS, if you are and is it in automation mode. If it is it moves the guests at will.

Do you db's have a high level of transactions, Maybe you can prove vmotion by moving low transaction

db's to gain their confidence. It is hard to overcome bias and ignorance when somebody refuses to look at the technology.

My manager used to say no vmotion at all during the day. Then drs came out and I let them know the systems will handle it

on it's own from now on. I have not had a complaint in years.

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acnsys
Enthusiast
Enthusiast

I work in a company where we use db applications for logging customers calls, invoices,...the whole nine yards a business shop is running.

The only reason i have been given so far is that one of the db will freaze if we vmotion it.

I use to remediate hosts during business hours and had never issues with it. Now i need to prove that none of the db requests will fail during a vmotion ( iknow barely nothing about db though). I was wondering if there was a doc. about this?

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BenConrad
Expert
Expert

This is a good test:

Get a good sized database and find a good sized index. Rebuild the index and then perform a vMotion. Everthing will work and the index job will continue to run on hostB. You won't see any errors in the Windows eventlog and you wont see any errors in the SQL log. Do this again and don't vMotion, compare results.

Ben

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demz
Expert
Expert

You can find two interesting links at the end of this post

http://c1tr1xguru.wordpress.com/2008/05/07/virtualized-oracle-database-can-be-migrated-with-zero-dow...

I think if Oracle certified itself VMotion as transparent, your manager has to believe it Smiley Wink

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