What is best RAID performance for a write intensive implementation
I have inherited a Synology RS815+ with 4 - 6TB hard drives. The RS815+ is going to be used as a backup only, so it will be write intensive. My question is what RAID level is the best for this application. RAID 1 would seem the best for speed and redundancy but would not be the best use of all of the disk space, as I understand it.
If I could have 2 Raid 1's that would be ideal.
Take it easy on the replies, my understanding of Raid is at the beginner level
If I could have 2 Raid 1's that would be ideal.
Take it easy on the replies, my understanding of Raid is at the beginner level
RAID 1 is NOT good for speed. It's good for redundancy but costly (as half the space is taken up by the redundant copy). It shouldn't be any slower than a single disk, but it's no faster either especially on writes.
If this is a backup only, then you already have redundancy, right? In which case, speed is your focus*. For speed, RAID 0 is best. BUT, there is ZERO redundancy in a RAID 0. None. If any disk fails, all data is lost. Generally RAID 5 or RAID 6 is good for speed and redundancy. RAID 5 provides for n-1 of disk space. Meaning, with 4 (n) drives of 6 TB, you get 18 TB of space (4-1 x 6TB). RAID 6 has the same net storage waste as RAID 10, RAID 0+1, and two mirrors. There are many articles explaining what RAID is, I'd suggest reading over them and trying to understand that first.
If this is a backup only, then you already have redundancy, right? In which case, speed is your focus*. For speed, RAID 0 is best. BUT, there is ZERO redundancy in a RAID 0. None. If any disk fails, all data is lost. Generally RAID 5 or RAID 6 is good for speed and redundancy. RAID 5 provides for n-1 of disk space. Meaning, with 4 (n) drives of 6 TB, you get 18 TB of space (4-1 x 6TB). RAID 6 has the same net storage waste as RAID 10, RAID 0+1, and two mirrors. There are many articles explaining what RAID is, I'd suggest reading over them and trying to understand that first.
I don't know the synology devices, but in more traditional server based RAID configs, the controller plays a HUGE role in performance. Software RAID is generally MUCH slower than a caching controller on a RAID 5 or 6.
ASKER
Am I correct in assuming that I can have only one Raid array per controller? In other words I cannot have 4 Raid 0 arrays, in this configuration
You only have 4 disks, right? You can't have a RAID 0 array of 1 disk. Did you look up the definitions of RAID? It seems redundant for us to re-post what's been posted a million times on numerous other web sites. If you have an issue understanding, then reference the one your using and we can try to clarify - no problem with that...
And it depends on the controller. Some controllers can't support more than one array (those are usually the poor quality, cheap controllers).
And it depends on the controller. Some controllers can't support more than one array (those are usually the poor quality, cheap controllers).
ASKER
If Im bothering you with my questions don't answer anymore
The last 2 sentences are the only thing that addressed my question, thanks for that
The last 2 sentences are the only thing that addressed my question, thanks for that
I've provided you answers. It's up to you take them.
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ASKER
In the end I went with Raid 10 because of the added redundancy. Although this is a backup,which is the redundancy, we decided that we want it to live in case the humans don't notice a problem with a disk.
RAID 4/5/6 always need extra I/O (read old data before replacement) to recompute the parity.
If you just want speed without any form of redundancy, Raid 0 will deliver that.... and also if one drive fails, the driveset is lost as a whole.
raid 4 has worst performance (Parity disk will be the bottleneck) raid 5 has one parity area, raid 6 has two (so less performance, higher survivability of errors).