bnaertt
Contributor
Contributor

Some VMDKS are getting striped twice when the policy states 1 stripe. VSAN 6.0 Disk Format 2.

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So I noticed this strange issue on my Virtual SAN. 99% of my VMDKs are correctly set up with 1 witness, and one raid 1 array with 1 HDD from two hosts. Such as in this image -

VSAN1.JPG

Now here is another VM, with the same storage policy creating a raid 0 of mirrors and utilizing more space than I care to provide to the VM.

VSAN2.JPG

I've tried reapplying the policies and nothing changes. It's not a huge deal, but I'm just curious what would cause this. Oh yeah, and the kicker is VSAN still says its compliant to the policy.

VSAN3.JPG

1 Solution

Accepted Solutions
ChristianDickma
Hot Shot
Hot Shot

This is perfectly normal under a number of situations, and does not constitute a bug. For example, we will do this any time a VMDK is larger than 255GB. We will also do this when disk space is low. See Cormac's blog series Virtual SAN (VSAN) - CormacHogan.com and specifically Part 23: http://cormachogan.com/2014/04/23/vsan-part-23-why-is-my-storage-object-striped/

I also want to clarify that unlike what you said a RAID-0 does NOT consume additional disk space. It is simply a means to split a mirror into smaller chunks. In sum the size doesn't change though.

As for compliance, if you check out the definition, StripeWidth is a _minimum_ number of spindles per mirror to use. VSAN is free to use more spindles. Also note in the above cases where we use RAID-0 we may place two stripes on the same disk, as long as satisfy the StripeWidth minimum of spindles the user asked for.

Christian

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2 Replies
jonretting
Enthusiast
Enthusiast

What is the status of your Storage Provider registration for that cluster? That might be the problem.  -Jon

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ChristianDickma
Hot Shot
Hot Shot

This is perfectly normal under a number of situations, and does not constitute a bug. For example, we will do this any time a VMDK is larger than 255GB. We will also do this when disk space is low. See Cormac's blog series Virtual SAN (VSAN) - CormacHogan.com and specifically Part 23: http://cormachogan.com/2014/04/23/vsan-part-23-why-is-my-storage-object-striped/

I also want to clarify that unlike what you said a RAID-0 does NOT consume additional disk space. It is simply a means to split a mirror into smaller chunks. In sum the size doesn't change though.

As for compliance, if you check out the definition, StripeWidth is a _minimum_ number of spindles per mirror to use. VSAN is free to use more spindles. Also note in the above cases where we use RAID-0 we may place two stripes on the same disk, as long as satisfy the StripeWidth minimum of spindles the user asked for.

Christian

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