Consumer (or prosumer) SSD's vs. fast HDD in a server environment
What are the pro's and con's of consumer SSDs vs. fast 10-15k spinning drives in a server environment? We cannot use enterprise SSDs in our case as they are prohibitively expensive. Here's some notes about our particular use case:
- Hypervisor with 5-10 VM's max. No individual VM will be crazy i/o intensive.
- Internal RAID 10, no SAN/NAS...
I know that enterprise SSDs:
- are rated for longer lifespans
- and perform more consistently over long periods
than consumer SSDs... but does that mean consumer SSDs are completely unsuitable for a server environment, or will they still perform better than fast spinning drives?
Since we're protected via RAID/backup, I'm more concerned about performance over lifespan (as long as lifespan isn't expected to be crazy low).
Note: This answer is specific to the server components described in the OP's comment.
- Compatibility is going to dictate everything here.
- Dell PERC array controllers are LSI devices. So anything that works on an LSI controller should be okay.
- Your ability to monitor the health of your RAID array is paramount. Since this is Dell, ensure you have the appropriate agents, alarms and monitoring in place to report on errors from your PERC controller.
- Don't use RAID5. We don't do that anymore in the sysadmin world.
- Keep a cold spare handy.
- You don't necessarily have to go to a consumer disk. There are enterprise SSD drives available at all price points. I urge people to buy SAS SSDs instead of SATA wherever possible.
- In addition, you can probably find better pricing on the officially supported equipment as well (nobody pays retail).
- Don't listen to voodoo about rotating SSD drives out to try to outsmart the RAID controller or its wear-leveling algorithms. The use case you've described won't have a significant impact on the life of the disks.
Also see: Are SSD drives as reliable as mechanical drives (2013)?
Yes, the SSDs will be way faster than the SAS drives. For sequential throughput, a good RAID of SAS drives might do pretty well, but for random access, the SSDs will blow them out of the water which can result in a very noticeable performance difference.
Depending on the particular SAS drives and the particular SSD drives, the SSDs may have a better unrecoverable read error rate by up to a factor of 10.
Some tips for if you do use consumer SSD drives:
- Know your write workload so you can estimate how often you'll have to replace the drives since they have a certain amount of write endurance
- If you can spare the space, overprovision the drives to make them more like enterprise ones
- Check out articles comparing the performance and write endurance characteristics of SSDs in the the same class and pick the one best suited to your needs
- Personally I'd get SSDs with a 5 year warranty because I believe the manufacturer is going to provide better quality as a result. I know this isn't a hard and fast rule, just personal belief.
- There are low end consumer SSD drives and higher end one - sometimes labeled something like "Pro" - you might want to look for ones in that class
- This goes for enterprise drives too, but be sure you're monitoring the MWI (media wear indicator) so you know when to replace the drives