Open / Free Space on a Lun

Software-based VM-centric and flash-friendly VM storage + free version

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cfsc
Posts: 4
Joined: Wed Jul 17, 2019 9:03 pm

Wed Jul 17, 2019 9:08 pm

Wondering recommendations and experience with open freespace on a LUN.
Most Best practice for any SAN i've used is to always have 20% open for snap shots, catching etc.

Can't find any printed material on this.

Wondering the options and implications. Want best practice of course.

Thanks Clark
Oleg(staff)
Staff
Posts: 568
Joined: Fri Nov 24, 2017 7:52 am

Thu Jul 18, 2019 8:25 am

Hi Clark,
It really depends on the environment and hypervisor you are using. Please follow the recommendations that are given by the vendors you are using in our environment.
cfsc
Posts: 4
Joined: Wed Jul 17, 2019 9:03 pm

Thu Jul 18, 2019 1:28 pm

Thanks Oleg

We are running a 2 node Starwind HyperConvered system. Running on Dell R740s with Vmware sitting on top.

Since the VSAN is running on a WINDOWS 2016 Datacenter OS... would we not have to meeting the windows Requirements?
Open space for repairs and such? I'm thinking windows throws warnings at 20%???

Then, what does Starwind need? Does it need a 10 for snaps etc....?

Then VMware requires 20% free for it's operations.

so a 10TB Partition on WIndows x .80 = 8TB that can be presented to VWMARE.
VMWare 8TB with 20% required free space = 6.4TB of actual space I can use on.

IS that not correct? Can you advise what I might be missing?

thanks Clark
Oleg(staff)
Staff
Posts: 568
Joined: Fri Nov 24, 2017 7:52 am

Thu Jul 18, 2019 2:10 pm

Clark,
Since the VSAN is running on a WINDOWS 2016 Datacenter OS... would we not have to meeting the windows Requirements?
Open space for repairs and such? I'm thinking windows throws warnings at 20%???
You are right for the disk where OS is installed. But you can use all space on the volume with StarWind devices.
Then, what does Starwind need? Does it need a 10 for snaps etc....?
We do not recommend to do snapshots of StarWind VMs, due to delays and possible problems with synchronization during snapshot creation.
so a 10TB Partition on WIndows x .80 = 8TB that can be presented to VWMARE.
No, you do not need to leave 20% on volume, where StarWind devices will be located.
cfsc
Posts: 4
Joined: Wed Jul 17, 2019 9:03 pm

Thu Jul 18, 2019 2:36 pm

Thank you again Oleg

So, let's start over with the math then.

1. the raid/disk/volume that Starwinds is using for the san is 10TB. We can present 100% of that to VMware with no issues?
2. So VMware get 10TB, and we use the 20% rule for them.. so our max space to use = 8TB (for Virtual Hard drives).

we only lose 20%

Correct?

(and of course since we have windows servers as VMs. We keep the standard windows buffer on those disks.

thanks Clark
cfsc
Posts: 4
Joined: Wed Jul 17, 2019 9:03 pm

Thu Jul 18, 2019 9:52 pm

We can close this.. I'm taking it up a bit more closely directly with the techs.
Oleg(staff)
Staff
Posts: 568
Joined: Fri Nov 24, 2017 7:52 am

Fri Jul 19, 2019 8:53 am

1. the raid/disk/volume that Starwinds is using for the san is 10TB. We can present 100% of that to VMware with no issues?

Correct.
2. So VMware get 10TB, and we use the 20% rule for them.. so our max space to use = 8TB (for Virtual Hard drives).
As I told you initially, it depends on your vendors recommendations :)
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