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Should SSD's run in RAID 5?

georgopanos
georgopanos used Ask the Experts™
on
I wanted to know if it would be smart to run Seagate Nytro Enterprise SSD mixed use drives in Raid 5
I have read mixed reviews about running ssd's in Raid 5 on a server. The server will have a few VM's and be a file server as well.
The drive I was looking at is the XA1920ME10063
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IT Product Manager
Top Expert 2009
Commented:
For enterprise class SSD drives being in a RAID is no more a problem. It was earlier not recommended to put the SSD drives into hardware RAID configuration because of TRIM technology which RAID controllers were not aware of. As a result the SSD drives got worn out quickly.
But now the SSD drives such a high endurance that your hardware can get old before your SSD drives go bad.
AlexA lack of information provides a lack of a decent solution.

Commented:
Unfortunately the above is not correct for this particular drive, from my understanding it's only Intel SSD's with an intel controller which fully support a RAID function with TRIM enabled.

Realistically, I'd probably go down the route of SAS drives and then if your RAID controller can do it, use SSD for caching. If it's going to be a file server you'll be making a ton of changes to the layout of the drives so.

Regards
Alex
If you are using spinning rust drives, do not use RAID-5, only RAID-1, RAID10 or RAID-6

For SSD drives you are free to use what RAID Layout suits you!
For  anything other than Enterprise sized configs, software RAID and SSD’s go together well
noxchoIT Product Manager
Top Expert 2009

Commented:
Alex, what is not correct in my post? TRIM was first in Intel but later almost all SSDs got it. But with enterprise class drives the TRIM is not important anymore because of amount of TBW they have. And the drive which the OP posted has the TBW of 10.5PB.
Again, TRIM was intended to prolong the life of SSD. And with expected lifetime of enterprise SSD one do not really need to care about it.
AlexA lack of information provides a lack of a decent solution.

Commented:
If you are using spinning rust drives, do not use RAID-5, only RAID-1, RAID10 or RAID-6

No, obviously they need to be in a RAID and then use SSD's for caching, it's cheaper, works well and would be better suited for this particular type of setup.


software RAID and SSD’s go together well

Software RAID is utter trash and frankly it goes well with nothing.
Top Expert 2014

Commented:
Enterprise SSDs don't need TRIM, they have enough free space to do garbage collection in background without being told what blocks are free.
There is a Seagate 2TB SSD for consumer use which does needs TRIM but the enterprise one you want to use is only 1.92TB because of the need for more reserved space to enable them to run on RAID controllers without TRIM.

BTW, it's not the RAID controllers fault they don't do TRIM with RAID 5 and 6, If they sent a TRIM command to one disk they would have to recalculate the parity for the stripe that block was in and write it again because even if that block is not needed for data it is needed for parity.

Author

Commented:
Unfortunately I am seeing two sides of the using raid and not with SSD's

if this helps the controller will be a Dell PERC H730P RAID Controller
Top Expert 2014

Commented:
You'd better read Dell's FAQ then, https://www.dell.com/support/article/uk/en/ukbsdt1/sln156240/dell-solid-state-drive-ssd-faq-with-servers-poweredge-and-storage?lang=en

"Current shipping Dell enterprise drives have high enough performance and endurance so they do not yet support these commands even if the OS supports them."

I'm pretty sure that is wrong and it is that the controllers don't (and can't) support TRIM/UNMAP.but anyway Dell says you do not need TRIM with enterprise SSDs.
Top Expert 2014

Commented:
Alternatively you could contact all the vendors listed at https://searchstorage.techtarget.com/definition/all-flash-array and tell them they shouldn't be using SSDs in their RAID arrays. As far as seeing two sides to something there are always at least two sides, some people claim the Earth is flat.
Philip ElderTechnical Architect - HA/Compute/Storage

Commented:
In small drive count settings we set up RAID 5. Four or five SATA or SAS SSDs.

Higher counts get RAID 6.

You're safe to run with parity RAID.  :)
Alex

software RAID and SSD’s go together well

Software RAID is utter trash and frankly it goes well with nothing.

I think you are behind with the times, Microsoft Storage Spaces and VMware’s vSphere Storage are both software products

On Windows software RAID-1 usually gives better performance than the low end RAID controllers and is much preferable on reliability grounds to those software assisted RAID chips on motherboards