Ubuntu – raid advice with SSD and two HDD

diskhard driveraidssd

I have a new machine with one 128GB SSD and two 1TB HDD. On the SSD is the OS and my initial thought was to put the two HDD in RAID 1 for user data.

After some more thought I came up with two other setups and now I'm in doubt 🙂 Can someone advise what would be the best setup?

1: single SSD and HDD in RAID 1 (original thought)

2: Create 2 partitions on the HDD (128GB and 872GB). Put the two 872GB in RAID 1 and create another RAID 1 with the SSD and one 128GB HDD partition.

3: Create 2 partitions on the HDD (750/250), put the 705GB in RAID 1 and use the 2 250GB as backup and make automatic snapshots of the SSD to (one of) these partitions.

I think the 2 main questions are:

Is it advisable to create a raid array with only part of a drive and actively use the other part of that drive or should you always use the full disk?

Is it advisable to create a raid 1 array with a SSD and HDD or will that blow the whole speed advantage of the SSD?

Best Answer

Is it advisable to create a raid array with only part of a drive and actively use the other part of that drive or should you always use the full disk?

The advice is always to use as much similar devices as you can. I'm not sure how much of that advice is superstition though, but lets look at this first:

Is it advisable to create a raid 1 array with a SSD and HDD or will that blow the whole speed advantage of the SSD?

No. Don't do that, you will blow the speed. Apart from the fact that they are different devices etc, the one thing I am quite sure of is that your speeds will drop, as you are going to be working at the speed of the slowest disk -> your ssd-hdd combo will be way slower then your SSD :

You should NOT do that to your SSD. Your first option is the best one. Just give yourself safe userspace, and speedy system disk. Backup that disk. (remember, RAID is not a backup strategy)

Related Question