Size of storage for PBS

[juluss]

Hi !

Here is the storage specs of my Proxmox VE :

• one 500gb SSD for the system and some VM
• one 1Tb HDD passthrought to an OMV VM. That VM is my Time Machine.

I plan to add a HDD on that, probably a 4Tb or 6Tb, with passthrought to an other VM. This will hold some big files (around 1 to 8gb files).

I want all this in backup, so I plan to build a Proxmox Backup Server. But I struggle to determine the size of the storage on that. I’m on a budget, this is for home use only. I already have the computer, all it needs is storage.

My idea is to take a drive that is 2Tb bigger than the new one on PVE. So if I buy a 4Tb for PVE, I’d buy a 6Tb for PBS. Or 6 and 8. That way I’ll have 2Tb left for the 500gb and 1tb.

I don’t know how long I should keep the backups. I’d say something in the months or one year maybe ? On all these VM there won’t be a lot of changes, the data will be mostly static. It will grow of course, but once it’s there it’s not supposed to really change.

Thanks !

 

[Dunuin]

Keep in mind that PBS needs IOPS performance. HDD only is basically a no-go. Either use SSD-only or ZFS with a HDD raid1/raid10 for the data + SSD mirror for the metadata.

And yes, some months or even years od retention is a good idea.

 

[juluss]

Thanks but I don’t really have the budget to go with SSD. As said it’s for home use only, I don’t need extra performances.

As I plan to have max 5,5Tb of mostly static data to backup (4Tb data on one vm, 1Tb data on other vm, and 0,5Tb SSD with all the OS drives), is a 6Tb drive enough for my backups ? Should I go a bit bigger, like 8Tb ?

 

[Dunuin]

Thanks but I don’t really have the budget to go with SSD. As said it’s for home use only, I don’t need extra performances.

Its not about extra performance you only need in an enterprise environment. There you should use SSD-only for fast restores. HDD+SSD is already the unrecommenden worse choice used in homelabs.

Very much simplified:
Store 6TB of backups and it will store roughly 3 million chunk files. Each GC task then needs to read+write the atime of all those 3 million files.
Lets say a HDD can handle 100 IOPS and you got 6 million IO. Then the GC task would run 6 million IO / 100 IOPS = 60000 seconds. So your disk would work for nearly a day at 100% utilization just to free up some space.

Maybe you once copied a very big folder of mp3s or text files that took ages to complete. This is the performance you can expect with a PBS on HDD-only, as everything will be max 4MB in size (usually more like 1-2 MB).

So it will work with HDD-only, but be painfully to unusable slow.

 

[juluss]

Well then I’m not so sure PBS is the right tool for me…

I was considering other solutions as well, but PBS seemed the simpliest for me.
I’ll think about that.