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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

Red Raid 10 vs RE Raid 6

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Scott Pultz

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I am considering these two 32tb-40 builds:

16 x WD Red 4Tb in Raid 10 (32Tb)
10-12 x WD RE 4TB in Raid 6 (32-40Tb)

I was leaning towards the Raid 10 build, but the price if the RE drives have really fallen recently. My data is backed up on LTO-6

Which way would you go and why? I suspect that the Raid 10 is safer due to less chance of a URE ruining things during a rebuild, but then again WD recommends only 5 drives with their Red disks. These will go into a Caselabs case with vibration dampening on each drive.

Thanks,

Scott
 
Interesting question - Jeff K? :smile:
 
Raid10 = every drive duplicated, in the same housing. If the raid controller or system is lost, you still might lose everything, and similar drive models tend to fail within a similar time frame. I would keep two independant raid5 units or make a raid6, and keep a few hot spares ready.
 
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So what you're suggesting is essentially 2 raid 5s that are then treated by the OS as raid 1?
 
If you want the greatest amount of redundancy, with the greatest amount of performance and storage space, go with a raid6 and two hot spares. If you need more storage and performance, go with a raid5 and a hot spare.

i probably would only do two raid5 setups if I needed mirrored data on different platforms, one raid5 NTFS for Windows and an HREF raid5 for the Mac OS, on a dual boot system.
 
Hard drives are better these days, but all drives have a 100% failure rate, over a long enough time frame. If you use consumer or prosumer drives, expect your raid to rebuild once or twice a year. SAS/enterprise drives generally last longer, but the safest thing to do is have more than one copy, in more than one location.

I would trust an HBA controller with SAS drives in a raid5 more than an integrated controller and prosumer drives in a raid6 with hot spares, but the former is also much more expensive.

But as a prime example, my 3ware controllers are no longer supported by Mavericks OS 10.9, but I was able to backup the raid volume from my Windows OS partition, replace the 3ware controller with an Areca HBA controller, re-initialize the raid and copy the previous material back to the new raid volume, and keep going

Also keep in mind, the more drives you have the higher the failure rate (the more eggs in one basket). A raid6 may not be justified with 4 or 8 drives, but getting into rack mounted units with 12, 16, and 24 drives or more, a raid6 with hot spares is a must.
 
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Raid 6 with scheduled parity verification is the way to go up to 16 drives. Having a dedicated hot spare is good advice as well with the current crop of SAS controllers rebuilding Raid 6's relatively fast. Raid 10 is used in larger than 16 drive arrays to limit the failure % growth for each disk added since each disk has a partner and only failures with both A1 and B1 for example fail the raid. However corruption can occur on Raid 10 and the controllers cannot deal with it as good as parity raids. So over all a Raid 6 is more reliable against Data corruption. Just remember raid is realtime data protection only. Not a backup.
 
Eric Bowen said:
Raid 6 with scheduled parity verification is the way to go up to 16 drives. Having a dedicated hot spare is good advice as well with the current crop of SAS controllers rebuilding Raid 6's relatively fast. Raid 10 is used in larger than 16 drive arrays to limit the failure % growth for each disk added since each disk has a partner and only failures with both A1 and B1 for example fail the raid. However corruption can occur on Raid 10 and the controllers cannot deal with it as good as parity raids. So over all a Raid 6 is more reliable against Data corruption. Just remember raid is realtime data protection only. Not a backup.
Click to expand...

I'm making double copies to LTO-6 which will hopefully (knock on wood) be enough. I may make a 3rd copy to USB drives.

I suppose that RAID 60 would be a safe way to double the size of a RAID 6 eventually down the road.
 
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