[SOLVED] RAID 1, RAID 10, or ?

[sub3marathonman]

OK, these are the parameters. I've got four drives, two WD enterprise 2TB SATA III, and two 500gb SATA III ssd drives. With the understanding that RAID is not for backup, I am trying to decide how to set these drives up. The focus is really to avoid, at any and all costs, any downtime at all. The total amount of data is possibly up to 1TB, but at the moment around 400gb. The 2TB drives were chosen more as an economic $/gb rather than a needed storage focus, but then ready if the future need occurs.

I could do RAID 10 with all four drives. I know, the insanity of it all, but wait. This would be on a somewhat long term but potentially changeable basis. This would give both data protection from disk failure, and at least theoretically a bit of return of speed. I'd give up 75% of the space on the hdd drives, but at some point I can get that back. Maybe by then I'd be getting a couple more 500gb SATA III ssd drives to keep the RAID 10.

I could do RAID 1 with two drives, and a separate RAID 1 with the other two drives. I know it kills the speed of the ssd drives, but I could do both as RAID 1 with the hdd and ssd. It of course would make more sense to do each RAID 1 with identical drives, install the OS on the RAID 1 ssd drives, but I have a nagging worry that identical drives fail at identical times.

I could do RAID 1 with the two hdd drives, and leave it as two separate ssd drives, as there doesn't appear to be much benefit with RAID 0 and ssd drives. The negative with this is that you'd install Windows 10 on the ssd, getting speed but gambling on the required safety of no downtime, or you'd go with the OS on the RAID 1 hdd drives for the safety but I'm thinking it would end up feeling fairly slow, although I might be wrong about that as the RAID 1 might bring it back enough at least for the read speed.

Any help is greatly appreciated.

 

[USAFRet]

The focus is really to avoid, at any and all costs, any downtime at all.

What is this system used for?

Almost any combination of those drives in a RAID array brings you either slower performance, smaller drive space, or both.

 

[alceryes]

The focus is really to avoid, at any and all costs, any downtime at all.

If this is the deciding factor go with two RAID 1 arrays.
Even if it would work, you should never create RAID arrays using different model drives. It's unsupported by controller manufacturers. I doubt it would even work if you tried to combine spindle and SSD drives.

 

[popatim]

R1 with an SSD & HDD gives you a drive the size of the smallest in the pair (= 500Gb).

R1 the data HHD's. Then another R1 for the SSD's.

You still have a chance at losing at the Data on either Raid but this is where your backups come into play and it sounds like you have that handled already.

 

[USAFRet]

I've got four drives, two WD enterprise 2TB SATA III, and two 500gb SATA III ssd drives.

With that combination of drives, the best you'll get is a 1TB array, with the blinding speed of a typical HDD.
At best.

 

[sub3marathonman]

I've got four drives, two WD enterprise 2TB SATA III, and two 500gb SATA III ssd drives.

With that combination of drives, the best you'll get is a 1TB array, with the blinding speed of a typical HDD.
At best.

Yes! Very true. But if I had to live with hdds, they should too!!

But of course the logical choice is what has been suggested, two separate RAID 1 arrays, one fast, one at hdd speed, but maybe a little faster since RAID 1.

I happened to find a posting by cirdecus back on 12/2/2011 (reaching back but still true), cirdecus post from 2011
and saying "
Typically, in a high performance desktop, you want to design your storage like this:

Two disks or disk groups:

1st Disk group should be a fast, low capacity volatile group.
2nd Disk group should be a slow, high capacity, highly redundant group. "
cirdecus also said, back in 2011, that similar drives fail at similar times, so the RAID 1 might not be as safe as poeple think.

As a theoretical question though, and my math might be off, is RAID 10 safer, equal, or less safe than two RAID 1 setups? This would be with the hdd mtbf of 2,000,000 hours, and the ssd with the mtbf of 1,500,000 hours. It just seemed that the ssd RAID 1 was at a bit more risk of failure. I keep thinking the RAID 10 will fail too at the time of an ssd failure, but you've still got the hdds with the longer mtbf to save everything.

And I will have the data backed up, I just don't want to lose the Windows 10 setup. And of course I don't want any downtime either with having to restore the data if that is on a separate RAID 1.

 

[USAFRet]

A RAID 10 with those 4 drives gives you the worst of both.
Small size and slow speed.

In the consumer space, there is rarely a need for RAID of nay type.
Again, what is this system for?

Drives are pretty reliable. And that is ALL any RAID can ward off...physical drive fail.
It does nothing for the more prevalent forms of data loss. Accidental deletion, virus, malware, corruption.
That is handled with actual backups.

And given a good backup routine, any "RAID" simply defers the downtime in case of a drive fail. Not prevent.
You'd still need to replace a drive and rebuild the array.

I had an SSD die suddenly a year ago. 960GB Sandisk, 605GB data on it.
Slot in a replacement drive, click click from the Macrium backup...up and running in an hour.
Probably faster than rebuilding a RAID array.

As far as "safer"...that s not really discernable for your small selection of drives. MTBF can be a good fleetwide indicator, but if your drive dies at 5 weeks, it is meaningless.
And 1,500,000 hours? OK...170 years of 24/7 ops.

Don't be so concerned about a drive dying....be more concerned about the data on that drive. A RAID does nothing for that.