[mdlug] Linux VMs - virtual disk best practices

[Aaron Kulkis]

Michael ORourke wrote:
> Which brings up the next logical question: how do you know if your virtual disks needs re-aligning?
>


You should properly align the storage when you set up the system.

Re-alignment is what is done after someone not-quite-competent has set up the system.

How do you know?  You basically have to wade through the disk, volume, and partition
data and look to see if proper boundary numbers are used.
Currently, divisibility by 4 is ALWAYS a good thing.


> -Mike
> ----- Original Message ----- From: "Dan Pritts" <danno at dogcheese.net>
> To: "MDLUG's Main discussion list" <mdlug at mdlug.org>
> Sent: Thursday, March 21, 2013 1:45 PM
> Subject: Re: [mdlug] Linux VMs - virtual disk best practices
>
>
>> You are correct that alignment is absolutely critical.
>>
>> However, my experience with vmware, at least, is that the virtual disks are aligned
>> properly.  So if you just throw your filesystem at a virtual disk I think you should
>> be just fine.
>>
>> If you find that virtual disks are not aligned properly then you are right, you could
>> compensate with the partition table.
>>
>> On Mar 21, 2013, at 11:41 AM, Jonathan Billings <billings at negate.org> wrote:
>>
>>> One of the reasons why partition tables are good on virtual disks is
>>> because you often want to make sure to align the partitions with the
>>> blocks of the underlying storage.  You don't want to have an unaligned
>>> partition to cross the underlying storage's stripe boundary.  You also
>>> want to make sure that the block size of the filesystem matches up to
>>> the stripe/block/chunk size of the underlying storage.
>>>
>>> There's a nice graphic on this blog post that does a good job of
>>> visually demonstrating alignment performance benefits:
>>>
>>> http://blogs.vmware.com/vsphere/2011/08/guest-os-partition-alignment.html
>>>
>>> --
>>> Jonathan Billings <billings at negate.org>
>>> _______________________________________________
>>> mdlug mailing list
>>> mdlug at mdlug.org
>>> http://mdlug.org/mailman/listinfo/mdlug
>>
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