Most cost effective and fastest RAID array?

Question

I had a SSD, and it failed and I lost all my data. Sad day..

What I want: To make a RAID 1 array to have all my data mirrored onto 2 drives and backed up. I want to use and have SSD speeds(important), but have my mirrored backup onto a cheap HDD because they are about 10x cheaper memory.

Question: is this possible to accomplish what I am wanting to do? If so how? what is the best method? Other suggested methods are welcome.

Now from what I have read, if I put together a RAID 1 array with a SSD and HDD, my SSD would perform as slow as the HDD, I do not want this. I need a better idea or the correct info

Thanks for your info and suggestions ^_^

Answer 1

It's a very bad idea to RAID1 between an SSD and a HDD.

In your situation, use a sync software to have automated backups fro SSD to HDD.

You can program them daily or at whatever time interval you want.

Answer 2

If the RAID hardware/software is aware of the speed difference, it will always (or almost always) read from your SSD.

As an example see -w option to mdadm:

-W, --write-mostly
subsequent devices listed in a --build, --create, or --add command will be flagged as 'write-mostly'. This is valid for RAID1 only and means that the 'md' driver will avoid reading from these devices if at all possible. This can be useful if mirroring over a slow link.

So you can have fast reads (from SSD), relatively slow writes (limited by HDD) and a protection from a single drive failure.

Not all RAID solutions can do this. E.g. according to this answer Btrfs lacked the desired options few years ago. I made a quick search and it seems the situation hasn't changed since.

Aside from that, since you used the word "backup", remember: RAID is not a backup.