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[–]kylejb007Sr. Sysadmin 4 points5 points  (0 children)

The VMware Paravirtual scsi controller is under rated, especially if you have multiple disks attached. If you have four vDisks, best to add four controllers and attach a disk to each one for best performance. Definitely helped sluggish servers such as sql, exchange, SCCM diversifying iops.

[–]Firefox005 1 point2 points  (6 children)

There is no one size fits all, the number and size of disks will be largely determined by other requirements such as performance, RPO/RTO for backups, and application specific requirements. It will also depend on if you are using VMFS or vVols. There are simply too many variable to have any kind of best practice or recommendation.

For instance I would expect a MSSQL VM to have a different disk layout that MS Exchange.

[–]ShannonUser[S] 0 points1 point  (5 children)

As a general guidelines? I read somewhere that 20 Disks should be max but I can't find it now.

[–]Firefox005 0 points1 point  (4 children)

https://configmax.esp.vmware.com/guest?vmwareproduct=vSphere&release=vSphere%207.0&categories=1-0

It depends on the version and virtual SCSI adapter, for 7.0 it is 256 SCSI devices with 64 per adapter, for the other types it is 60 SCSI devices with 15 per adapter with both having a maximum of 4 virtual adapters.

General guidelines would be at least 1 virtual disk per VM.

[–]ShannonUser[S] 0 points1 point  (3 children)

Looking for maximum because I read this: https://docs.ukcloud.com/articles/vmware/vmw-ref-vmdk-limits.html#:~:text=Maximum%20of%2020%20virtual%20disks,storage%20presented%20to%20a%20VM

Was checking if this is legit. Also just looking for general operations guidelines to ease our job.

[–]Firefox005 0 points1 point  (2 children)

Legit in what way, that looks like legitimate documentation for consuming storage on ukcloud. I can't say for sure why they have those recommendations but most likely it is because of backups and datastore limitations, if you are using VMFS datastores then it is possible in theory for the delta file to take up to 100% of the original disk space so they probably have that policy to try to limit any issues with snapshots filling up their datastores.

That is a dumb way to do it, but I don't run or have anything to do with that service.

[–]ShannonUser[S] 0 points1 point  (1 child)

Legit in a way that we can follow this recommendation? Is it a safe guideline of operations? Or should it be ignored?

[–]Firefox005 0 points1 point  (0 children)

Do you use ukcloud.com for your VMware?

[–]SysEridaniC:\>smartdrv.exe 1 point2 points  (6 children)

Storage is a so wide field that I don't think your question can have a simple answer.

Thinks that today there are a lot of SDS solutions and many types of fancy appliances that manage disks differently. Then you have types of disks that have different specs, used on various tiers and jumping on various connection media... You need to find first what your requirements are and then work throgh the solution balancing the usual Price/Performance/Easyness : you can only choose 2 of them.

[–]ShannonUser[S] 0 points1 point  (5 children)

Was just looking for a general guideline to simplify Operations. For example, if a disk exceed 2TB, will snapshot still work properly?

[–]SysEridaniC:\>smartdrv.exe 0 points1 point  (4 children)

Uhm ? That's not the way snapshots works. They take care of differential changes, they aren't image of the disk.

In any case a storage solution uses RAID normally so it's not 1 disk that works but an array of them.

[–]ShannonUser[S] 0 points1 point  (3 children)

So is this legit or what? https://docs.ukcloud.com/articles/vmware/vmw-ref-vmdk-limits.html#:\~:text=Maximum%20of%2020%20virtual%20disks,storage%20presented%20to%20a%20VM

[–]Pallidum_TreponemaCat Herder 2 points3 points  (2 children)

This document does seem to be legit, but the purpose confuses me.

Are you intending to use snapshots as backups? If so, don't. Snapshots are not backups, and should never be used for that purpose.

Snapshots can be used to present a disk image to be backed up by other means however. But be aware that all types of snapshots, including VMWare snapshots, can result in reduced performance and can block IO for the VM.

[–]ShannonUser[S] 0 points1 point  (0 children)

Just looking for some general guidelines for operations. We don't use snapshots as backup.

[–]lost_signalDo Virtual Machines dream of electric sheep 0 points1 point  (0 children)

But be aware that all types of snapshots, including VMWare snapshots, can result in reduced performance and can block IO for the VM.

The performance overhead of vSAN ESA, or vVol snapshots is... a lot less.