user: I'm installing a KVM VM-server with a fast SSD drive ans a large disk RAID array. Would it make sense to give each VM it's own swap space on the SSD? And do I need a separate LVM group on the SSD to make sure the swap volumes will be located on the SSD?

assistant: Yes, it makes sense to give each VM its own swap space on the SSD. This will ensure that each VM has its own dedicated pool of fast memory for swapping, which can improve performance and prevent contention. You do not need a separate LVM group on the SSD, but it is a good practice to do so. This will make it easier to manage the swap volumes for each VM and ensure that they are always located on the SSD.

Here are the steps on how to set up swap space for each VM on the SSD:

1. Create a separate LVM group on the SSD.
2. Create a swap volume for each VM in the LVM group.
3. Set the swappiness parameter for each VM to a low value, such as 10.
4. Restart the VM.

The swappiness parameter controls how aggressively the kernel will swap memory out to disk. A lower value means that the kernel will be less likely to swap memory out, which can improve performance.

Here are some additional things to keep in mind when setting up swap space for VMs:

* The size of the swap volume should be at least the same size as the amount of physical memory for the VM.
* You can also use a swap file instead of a swap volume. However, a swap file will be slower than a swap volume on an SSD.
* If you are using a KVM hypervisor, you can use the `virsh` command to manage the swap space for VMs.

I hope this helps!

user: I'm using a RAID array for my storage. Would it be better to put the swap space on the SSD or the RAID array?

assistant: It is generally better to put swap space on the SSD rather than the RAID array. This is because SSDs are much faster than traditional hard drives, and the performance of a swap space is critical for the overall performance of the system. When a system runs out of physical memory, it will start to swap pages of memory to disk. This can be a very slow process, especially on a traditional hard drive. However, it will be much faster on an SSD.

In your case, since you are using a RAID array for your storage, you can put the swap space on either the SSD or the RAID array. However, I would recommend putting it on the SSD for the best performance.

Here are some of the benefits of putting swap space on an SSD:

* Faster performance: SSDs are much faster than traditional hard drives, so the swap space will be much faster.
* Reduced wear and tear: SSDs have a limited number of write cycles, so putting swap space on an SSD will help to reduce the wear and tear on the drive.
* Improved reliability: SSDs are more reliable than traditional hard drives, so putting swap space on an SSD will help to improve the reliability of the system.

If you are concerned about the lifespan of the SSD, you can always use a smaller swap space. However, I would recommend using at least the same amount of swap space as the amount of physical memory for the VM.

user: I see. So it would be better to put the swap space on the SSD for better performance. But you mentioned that SSDs have a limited number of write cycles. So if I put the swap space on the SSD, wouldn't that shorten the lifespan of the SSD?