Backup Storage - RAID Level
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@wirestyle22 said in Backup Storage - RAID Level:
It's true that Raid 1 is the fastest thing you can do with two drives and have redundancy. I always thought Raid 10 was the best option, but that comes with a pretty hefty cost. I can see what you are saying in regards to cost vs. capacity.
RAID 1 is just the smallest RAID 10 if you think of it that way. RAID 10 where the RAID 0 stripe is just one drive, that's RAID 1. So while that's weird, it's the only useful way to really think of it. RAID 1 as a subset of RAID 10 because that's how it behaves (if you make a curve of any RAID 10 function - capacity, performance, reliability, cost, etc.) RAID 1 fits neatly in as the smallest entry. And since lots of controllers allow for "single drive RAID 0 implementations" it is logical that we would see RAID 1 as a small RAID 10 as well.
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@wirestyle22 said in Backup Storage - RAID Level:
I'd trade the performance for more redundancy in this kind of a situation.
This is where you differ from the norm. The vast majority of businesses will not invest additionally in extreme levels of data protection in their backup systems. Remember, this is already a backup, if the system fails you can recreate it. This is so extreme that many people argue for RAID 0 and RAID 5 on backup systems. It is already a full extra level of complete redundancy itself, so making it even more redundant is redundancy of redundancy. So normally it is only the speed of RAID 10 that comes into play, not the additional safety. If a backup system is lost because of RAID 6 or suffers large scale performance degradation it rarely matters at all. The cost of RAID 10 is extremely rarely a viable business case for backup systems.
That said here are the hard rules....
- Two drives, RAID 1
- Three drives, buy another drive
- Four drives, RAID 10
- Five drives, RAID 6
- Six or more drives.... weigh your priorities to determine what makes sense for your business case.
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@scottalanmiller said in Backup Storage - RAID Level:
@wirestyle22 said in Backup Storage - RAID Level:
@scottalanmiller said in Backup Storage - RAID Level:
Depends on many factors, but you typically use a large number of large capacity spinners (Winchester drives) for backup storage and RAID 6 is the most common approach. But it depends. If you are backing up a small amount, RAID 1 would make more sense up to 8-10TB today. And RAID 5 makes more sense if you are backing up to SSD. And RAID 10 might be important if you have a write bottleneck with your drives otherwise.
But by and large, RAID 6 is what you find until you get to something enormous running on ZFS, then RAID 7.
Raid 1: meaning speed isn't a factor at that low of a capacity?
What do you mean? RAID 1 is the fastest thing that you can do with just two drives. And is faster for writes than RAID 5 with four drives, RAID 6 with six drives or RAID 7 with eight drives.
It is? In all of those cases? Does RAID hardware make any difference, say 1GB cache etc?
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@Dashrender said in Backup Storage - RAID Level:
@scottalanmiller said in Backup Storage - RAID Level:
@wirestyle22 said in Backup Storage - RAID Level:
@scottalanmiller said in Backup Storage - RAID Level:
Depends on many factors, but you typically use a large number of large capacity spinners (Winchester drives) for backup storage and RAID 6 is the most common approach. But it depends. If you are backing up a small amount, RAID 1 would make more sense up to 8-10TB today. And RAID 5 makes more sense if you are backing up to SSD. And RAID 10 might be important if you have a write bottleneck with your drives otherwise.
But by and large, RAID 6 is what you find until you get to something enormous running on ZFS, then RAID 7.
Raid 1: meaning speed isn't a factor at that low of a capacity?
What do you mean? RAID 1 is the fastest thing that you can do with just two drives. And is faster for writes than RAID 5 with four drives, RAID 6 with six drives or RAID 7 with eight drives.
It is? In all of those cases? Does RAID hardware make any difference, say 1GB cache etc?
The assumption here is that the only difference is the number of drives.
So, yes, RAID hardware/software/cache makes a difference, but that isn't what's being discussed here.
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@Dashrender said in Backup Storage - RAID Level:
@scottalanmiller said in Backup Storage - RAID Level:
@wirestyle22 said in Backup Storage - RAID Level:
@scottalanmiller said in Backup Storage - RAID Level:
Depends on many factors, but you typically use a large number of large capacity spinners (Winchester drives) for backup storage and RAID 6 is the most common approach. But it depends. If you are backing up a small amount, RAID 1 would make more sense up to 8-10TB today. And RAID 5 makes more sense if you are backing up to SSD. And RAID 10 might be important if you have a write bottleneck with your drives otherwise.
But by and large, RAID 6 is what you find until you get to something enormous running on ZFS, then RAID 7.
Raid 1: meaning speed isn't a factor at that low of a capacity?
What do you mean? RAID 1 is the fastest thing that you can do with just two drives. And is faster for writes than RAID 5 with four drives, RAID 6 with six drives or RAID 7 with eight drives.
It is? In all of those cases? Does RAID hardware make any difference, say 1GB cache etc?
yes. The speed of the RAID is the speed of the RAID. You are talking about the storage subsystem as a whole, not the speed of the RAID itself now.
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Hardware makes the RAID 1 speed win more dramatic actually.
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Aww, yeah that makes sense.
I keep getting stuck on the fact that a single (or RAID 1) drive (winchester) itself is so slow, so easy to saturate its throughput that is almost seems useless today. Of course this could be expanded out to then say, well if RAID 1 is useless, then RAID 5, 6, etc are even more so.
Please don't take that to be me saying RAID 1 is useless, of course it's not. Using RAID 1 for work loads that don't need a ton of storage or throughput, RAID 1 is great.
