Hello,

 

My current Unraid system is a PC with only one drive - an SSD. I'm using this on a temporary basis until I get a new system that will have 4 HDDs.

 

I'm planning on installing the old SSD into the new system so that my data is retained, meaning it would come to a total of 5 drives.

 

The system has a VM and a few Docker apps.

 

Given the drive from the old system is an SSD, I'm thinking it would be best to repurpose it as a cache drive in the new system? Currently it is just assigned as a single array drive.

 

• What would be the best way to do this?
• Should I designate the drive as a cache drive on the old system beforehand, or would this result in data loss? (Presumably, there is no functional difference between an array and cache drive if you only have one drive) If not, at what point would I assign it as a cache drive from an array drive?
• Anything I should know before moving everything over to a new system?

 

Thanks!

 

If you keep the same file system type then it should be possible to assign the SSD as a pool device (which you can then use for caching purposes) on the new system and it’s data will be retained.    
 

This would not be the case if you wanted to change the file system type as that resulted formatting the  drive erasing any current contents.

So I should assign it as a pool device now (on the old system)? Do you have a link for how to do this? Thanks

If it's the only device you need to keep in the array, as Unraid requires at least one array data device assigned.

So I'd have to keep it as an array device and then reconfigure once on the new system?

 

Once on the new system, if I change Disk 1 to be a cache drive would I lose all the data on it, or would it be transferred to the other drives in the pool? The process doesn't seem very intutive to me. I'm always scared to make changes to avoid inadvertenly losing data.

6 minutes ago, superRaid said:

Once on the new system, if I change Disk 1 to be a cache drive would I lose all the data on it, or would it be transferred to the other drives in the pool? The process doesn't seem very intutive to me. I'm always scared to make changes to avoid inadvertenly losing data.

If you keep the file system type the same the data will still be there on the drive (which is now a cache drive).  If the relevant shares are set to Use Cache=Yes and pointed at that cache drive mover will subsequently transfer the data to the array.