This is correct. You can run the scan against the snapshot, but not the alignment process. The VM still has to come down for that. Also, for those that want to speed up the alignment process that aren’t up to running the tools on a Linux host (for NFS only), storage controller offload has been added in the most recent HUK and can be used if you’re running OnTap 7.3.5+ or 8.0.1+. This bypasses the memory limitation available in the Service Console of the ESX host and lets the controllers handle the heavy lifting. The only way around this previously was to use a Linux VM or physical box with 2GB+ RAM.
Also, many people aren’t aware but there’s an alignment best practices and procedures guide available here: http://media.netapp.com/documents/tr-3747.pdf
From: toasters-bounces@teaparty.net [mailto:toasters-bounces@teaparty.net] On Behalf Of Jack Lyons
Sent: Friday, August 26, 2011 9:45 PM
To: toasters@teaparty.net
Subject: Re: AW: Sources of unaligned IO other that Vmware? - pw.over_limitpersists
you can run the scan on a snapshot to determine if you need to run an mbralign. I don't think you run the align while the vm is up - I think at best you would only get a crash consistent copy that was valid as of the time of the beginning of the align and have to take an outage to reboot the vm off the aligned vmdk.
Jack
On 8/26/2011 8:10 PM, Alexander Griesser wrote:
I don’t think that this will work – but I’m going to try that out on Monday unless the OP clarifies that he didn’t mean it like that J
Running mbralign is a long-lasting process, especially for really big vmdks, but we always worked around that by having small „system“ or „boot“ vmdks and added additional disk space by adding additional vmdks which we initialized with GPT right from the start.
Later on, we created default templates with already aligned but empty disks which also works a treat.
Bye,
Alex
Von: toasters-bounces@teaparty.net [mailto:toasters-bounces@teaparty.net] Im Auftrag von Fletcher Cocquyt
Gesendet: Samstag, 27. August 2011 01:47
An: Chris Muellner; Eugene Vilensky
Cc: toasters@teaparty.net
Betreff: Re: Sources of unaligned IO other that Vmware? - pw.over_limitpersists
Holy Shnikies – does this actually work? And is it supported? (running mbralign with a snapshot, then (presumably) deleting the snapshot to merge the delta files back into the newly aligned vmdk – brilliant!)
We took downtime on all VMs to align them – the big ones took hours...even with 10gig networking – can’t believe I had not seen mention of this before.
How do you deal with the linux VMs which need boot file modification post alignment to (re)boot successfully?
FWIW, all our VMs are aligned now – we run a daily mbrscan report to pickup any stray misaligned vmdk files (usually they are virtual appliances)
On 8/26/11 1:05 PM, "Chris Muellner" <chris@northlandusa.com> wrote:
If you take a NetApp snapshot of the datastore then you can run the mbralign scan against the snapshotted -flat.vmdk(s) without having to power off the virtual machines.
--
Fletcher Cocquyt
Principal Engineer
Information Resources and Technology (IRT)
Stanford University School of Medicine
http://vmadmin.info
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