1 large vdisk vs smaller ones

[virtualizingtheworld]

Hi,

For vSAN (but not limited) do you recommend 1 large vdisk ex20TB or 4 smaller 5TB?

Any benefits/space savings etc behind the thoughts?

thanks

[a_p_]

IMO it's not a question of large vs. small.

What are your (the VMs) needs? How fast do you need to recover the virtual disk, in case that's necessary? ...

André

[TheBobkin]

Hello andvm​

I would generally advise 4x5TB over 1x20TB - from a manageability perspective these will generally have a better change of whole replicas (or their sub-components in the case of RAID5) being able to be stored on a single host/disk-group - this can have implications with regard to not only how it is stored but repairability in the case of a failure, it *may* also have improved performance but this depends on a lot of factors.

Also in the case that you have more failures than the FTT can tolerate, it may be faster and easier to restore single 5TB vmdk over 20TB, it may also back-up faster as we have more end-points.

Resync of multiple vmdk over one would be faster if on a version <6.7 U3.

Bob

[IRIX201110141]

vSAN, vDisk?

Do you mean vDisk/VMDK of a VM aka large file server VM or does vDisk means like Virtual Disk from a Raid controller?  vSAN needs pDisks as single/passtrough or raid0.

About vSAN... max. component size is around 255GB so every larger vDisk/VMDK will be automatically split into multiple parts.

From a VM perspective...

- multiple vDISK, each on its own SCSI Controller

- Not all eggs into one basket

- Each Disk can be have its own policy

- You can backup restore smaller single vDisks instead a large one

- If using windows... there is DFS to create a single file share tree from different locations.

Take a look to Very Large VMDK Considerations | VMware® vSAN™ Design and Sizing Guide | VMware

Regards,
Joerg

[virtualizingtheworld]

TheBobkin​

IRIX201110141​

Very good points thanks, I think that is enough to justify smaller VM vdisks where possible as there is potential for greater flexibility, performance and quicker recovery.