I have a workstation system that will have two 64GB industrial SSDs, and the plan is to have both disks in a RAID1 configuration for redundancy which is set up in the kickstart. The system will be running CentOS 7. In looking into this, I discovered that the RHEL Storage Administration Guide doesn't recommend RAID1 for SSDs.
Red Hat also warns that software RAID levels 1, 4, 5, and 6 are not recommended for use on SSDs. During the initialization stage of these RAID levels, some RAID management utilities (such as mdadm) write to all of the blocks on the storage device to ensure that checksums operate properly. This will cause the performance of the SSD to degrade quickly.
Is this something I should be seriously concerned with? Are there alternatives for redundancy that I can use?
According to RHEL documentation again, LVM mirroring now leverages MD software RAID, so the RAID warning also applies to that.
More info:
The SSDs are Swissbit X-200 series (SATA), and it looks like overprovisioning is at 40%.
Hardware RAID won't be an option, according to the hardware team.
Best Answer
I wouldn't quite recommend Linux software RAID with SSDs, especially for boot. I'd make the decision based on the potential failure scenario(s) and what the impact of downtime is. For industrial SSDs, I've typically used them standalone, without RAID.
If this workstation were to fail, how quickly can you 1). recovery from backups or 2). rebuild/reimage?
What type of SSDs are these (make/model)? If they're overprovisioned, this may not be too much of an issue. If they're SATA and connected to the motherboard, you'll have some TRIM options.
You can use an entry-level LSI hardware RAID controller to ease deployment and recovery. At least the underlying RAID will be transparent to the OS.
Edit:
These are highly overprovisioned industrial SSDs. Configure the RAID 1 mirror as normal and just monitor the drives over time.