quick question with 4bay NAS

[PUN]

4TB x 4 = 12TB with RAID 5. Is this the best way to go?
Any suggestions? TIA

 

[Emulex]

No i'd not recommend raid-5 with 4tb sata drives. Too much raid loss potential. Maybe raid-10 or RAID-1 or RAID-6 at the least!

 

[PliotronX]

Granted RAID-5 is not the best performance-wise or without a hot spare the best in parity but to maximize space it would be the best in this case. When one drive craps out, I have never seen a hot spare really utilized (in consecution) and with RAID-10 which I like for performance, you cut your space in half. NAS does not need the speed of 10 so I would say stick with RAID-5 and tweak the stripe size to at least 128KB.

 

[kevnich2]

First, I will insert obligatory raid is NOT a backup mechanism. After that, go with RAID 5. assuming this is for home and not mission critical business data. In which case, RAID 6 or 10

 

[kevnich2]

Just so you know the reason behind not going with RAID 5 for large hard drives anymore. RAID 5 uses parity with 1 drive for an N-1. If you have a drive in the array that dies, you're left with two and still able to function but it's going to warn you to replace the dead drive. When you do, it then scans the remaining two intact drives to populate the 3rd drive from parity data. What many have discovered is that there are usually also errors on one or more of the remaining drives so during rebuild process, when it encounters an error, it may drop another drive...making your array now dead because RAID5 can only survive one drive dying. This is also applicable if you use a hot spare as it still has to search the remaining drives for parity.

RAID 6 allows two drive failures. Even better is RAID 10 which is RAID 1+0

This wasn't really an issue with smaller drives back in the day but now with drive sizes in the 4tb range, it's happening more and more such that RAID 5 is no longer recommended.

 

[Essence_of_War]

4TB x 4 = 12TB with RAID 5. Is this the best way to go?
Any suggestions? TIA

For 4 drives, I'd go with a a stripe across mirrors (RAID 10). Better protection from drive failures, and when a drive dies, your rebuilds will be MUCH faster than either a RAID-5 or a RAID-6.

 

[PliotronX]

Just so you know the reason behind not going with RAID 5 for large hard drives anymore. RAID 5 uses parity with 1 drive for an N-1. If you have a drive in the array that dies, you're left with two and still able to function but it's going to warn you to replace the dead drive. When you do, it then scans the remaining two intact drives to populate the 3rd drive from parity data. What many have discovered is that there are usually also errors on one or more of the remaining drives so during rebuild process, when it encounters an error, it may drop another drive...making your array now dead because RAID5 can only survive one drive dying. This is also applicable if you use a hot spare as it still has to search the remaining drives for parity.

RAID 6 allows two drive failures. Even better is RAID 10 which is RAID 1+0

This wasn't really an issue with smaller drives back in the day but now with drive sizes in the 4tb range, it's happening more and more such that RAID 5 is no longer recommended.

Thank you, that makes sense. The RAID-5 arrays I have been monitoring have all been small drives (15K). Further, when a drive conks out and it is replaced (hopefully), 5 takes forever to rebuild the array. To find out that it may never successfully be rebuilt with larger drives is shocking. RAID-10 it is, in that case.

 

[PUN]

Thank you so much guys!
It's for my home backup and 8TB would suffice with RAID 10.