cargex
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VMware vSAN - How to add more HDDs to a Disk group
Hi Guys,
I have a vSAN in a vSphere cluster environment with 3 ESXi hosts.
Each host has a disk group configured with 1 SSD (750GB) and 5 HDD (3TB each).
I need to add more storage and I have physical bays available.
Now my first thought is to add 2 HDDs (3TB each) to each ESXi host and then add them to each host disk group.
Question1.
Is there a maximum number of HDDs per disk group? or can I keep just adding HDDs?
Question 2.
Is there a maximum storage size limit given the fact that I have only 1 SSD (750GB) per disk group?
Question 3.
Is the process as easy as properly turning off the ESXi host adding the new HDDs and when it turns on will it just add the new HDDs to the disk group that was created in that ESXi host?
Thanking you in advance,
Cargex
I have a vSAN in a vSphere cluster environment with 3 ESXi hosts.
Each host has a disk group configured with 1 SSD (750GB) and 5 HDD (3TB each).
I need to add more storage and I have physical bays available.
Now my first thought is to add 2 HDDs (3TB each) to each ESXi host and then add them to each host disk group.
Question1.
Is there a maximum number of HDDs per disk group? or can I keep just adding HDDs?
Question 2.
Is there a maximum storage size limit given the fact that I have only 1 SSD (750GB) per disk group?
Question 3.
Is the process as easy as properly turning off the ESXi host adding the new HDDs and when it turns on will it just add the new HDDs to the disk group that was created in that ESXi host?
Thanking you in advance,
Cargex
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Hi Andrew,
I currently have 5 magnetic disks in each disk group; so according to the figures you just explained I can add only 2 more magnetic disks to each disk group.
that is correct as per maximums for vSAN. and also this document
Configuration Maximums vSphere 6.0
Question:
Let's say I add magnetic disk number 8 in the ESXi host, how can I make use of that new storage space?
Do I have to create a brand new disk group?
Maybe a brand new vSAN data store configuration all together???
And if so, I would need to buy an additional SSD drive?
You would need to create a new disk group, and again with 1 SSD and at least 1 magnetic disk.
You should really read and get a good understanding of the Design Guide here, the guys at VMware spent a lot of time writing this, and try to make it clear.
VMware Virtual SAN 6.0 Design and Sizing Guide
ASKER
In that case I really need to make the best out of the 2 extra magnetic HDD that I can currently add.
Final question:
All of my current magnetic disks have a capacity of 3TB.
Is it Ok if I add 2 magnetic disks with a capacity of 6TB to each disk group?
By the way thanks for the document.
Final question:
All of my current magnetic disks have a capacity of 3TB.
Is it Ok if I add 2 magnetic disks with a capacity of 6TB to each disk group?
By the way thanks for the document.
Yes, you can add different sized disks.
but also check you have enough Flash Cache, as calculated above.
you need flash cache, for the size of the virtual machine disks.
but also check you have enough Flash Cache, as calculated above.
you need flash cache, for the size of the virtual machine disks.
ASKER
Based on that equation my SSDs are already at capacity in regards to that 10%.
If I add the 2 extra HDDs to my configuration I will go under that recommendation to a 7% more or less.
Question:
I'm guessing that I can do it anyway but the performance will be affected.
Is there a way to calculate how bad is the performance going to be affected?
If I add the 2 extra HDDs to my configuration I will go under that recommendation to a 7% more or less.
Question:
I'm guessing that I can do it anyway but the performance will be affected.
Is there a way to calculate how bad is the performance going to be affected?
Is this based on virtual machine disk (vmdk) capacity in use, and NOT adding additional storage.
Read and Write performance will be affected, this is the recommendation from VMware, the ratio should be 10%, and not t fill up a vSAN datastore.
Your are asking to calculate the unknown!
Read and Write performance will be affected, this is the recommendation from VMware, the ratio should be 10%, and not t fill up a vSAN datastore.
Question:
I'm guessing that I can do it anyway but the performance will be affected.
Is there a way to calculate how bad is the performance going to be affected?
Your are asking to calculate the unknown!
ASKER
Mr. Andrew
Understood.
Thank you very much for all your help, very eye opening as usual.
Understood.
Thank you very much for all your help, very eye opening as usual.
ASKER
I currently have 5 magnetic disks in each disk group; so according to the figures you just explained I can add only 2 more magnetic disks to each disk group.
Question:
Let's say I add magnetic disk number 8 in the ESXi host, how can I make use of that new storage space?
Do I have to create a brand new disk group?
Maybe a brand new vSAN data store configuration all together???
And if so, I would need to buy an additional SSD drive?