Hi Guys,
just wondering if you could achieve slightly better performance out of a Drobo (2nd-gen) by using faster (10.000 rpm) or higher cache spec hard drives? (and maybe make them all the same?) It could well be the Drobo's operating system or FW800 connection is more of a bottleneck for performance then the drives, I don't know.
Hope someone had experience with this or can share a little insight, thanx in advance!
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Will you get better perfomance out of a Drobo by using better/faster harddrives?
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From experience not really. I have two 2nd Gen 4 bay drobos and I have all 7200 rpm enterprise grade drives in one and normal 7200 rpm drives in the other and there isn't a real difference in speed. To make it worse the performance on the Drobo is not as fast as my single drive external hard drive over firewire 400 when I am using either the fw 800 or the USB connection on the drobo.
Even when I was working with Drobo support they were pretty happy when I was getting 30 MB/sec over FW800 while I was able to push 40+ MB/sec with a single drive FW800 connected drive.
Go with the middle of the line cost effective drives and don't worry about buying high end drives for the 2nd gen unit. On the other hand you might get a boost if you go to one of the newer enclosures as they have newer faster processors that are able to provide better performance possibly up to the point that the drives were the bottle neck instead of the beyondraid processor.
As for making them the same drive... The beyond raid will run into some performance hits if you fill it to the point that it can't span the data over all 4 drives. so for example if you have 3 x 2tb drives and then a single 500gb drive you will hit a performance wall at the 1.5 tb mark when it starts to have to span 3 drives instead of 4. At that point the drobo will keep trying to move stuff around so that the 4 drive section is as full as it can be. So while you can mix drive sizes it is really beneficial to try to keep as much if not all of the data able to fit in the 4 drive span.
For another example lets go with having a 500gb, 1tb, 1.5tb and 2tb drive in the drobo.
The first 1.5 tb can fit in a 4 drive "strip" because it takes 500 gb (the smallest drive) and runs that across all 4 drives but uses one drive of space for the redundancy.
The next 1tb will be made of 500gb from each of the 1tb, 1.5b and 2tb drives with one 500gb chunk used for redundancy.
The next 500gb will be made of 500 gb from the 1.5 and the 2tb drive with the data mirrored between those chunks.
There will be 500 gb on the 2tb drive that is "reserved for future expansion" a nice way of saying lost because we can't protect it.
Now the drobo will try to fill the 4 drive slice first then the 3 drive then the 2 drive. Then in the background as you delete, move or change files the drobo will try to find data to fill in the lower levels with more drives as much as it can. While that processes is happening in the background it is still happening and using up cycles to do it. On the other hand if you just had 4 x 1tb drives you would always be in the sweet spot of writing to 4 drives and you wouldn't have the lost top end space. Now if you replace the 500gb drive in the above example with another 2tb drive you end up with something like this:
4 drive protection = (1tb x 4) - 1 tb for redundancy = 3tb of data
3 drive protection = (500 gb x3) - 500gb = 1tb of data
2 drive protection = (500gb x 2) - 500gb = 500gb of data
None lost to future expansion reservation for ~$150 from that original stair step configuration.
The drobo website is really bad at explaining the magic of Beyondraid they just go with a trust us approach and I tried to find a really good article that broke down the patent filing for the technology. But that was a failure. Here is one that gives examples etherealmind.com/drobo-how-beyond-raid-works/ and if you google for how beyondraid works.
To summarize:
With the 2nd gen enclosure you won't get enough better performance (or any really) by adding really expensive drives.
If you want better performance you probably want to get a newer enclosure with a faster processor.
You will get better performance by ensuring as much of your data is on a 4 drive slice as you can.
Even when I was working with Drobo support they were pretty happy when I was getting 30 MB/sec over FW800 while I was able to push 40+ MB/sec with a single drive FW800 connected drive.
Go with the middle of the line cost effective drives and don't worry about buying high end drives for the 2nd gen unit. On the other hand you might get a boost if you go to one of the newer enclosures as they have newer faster processors that are able to provide better performance possibly up to the point that the drives were the bottle neck instead of the beyondraid processor.
As for making them the same drive... The beyond raid will run into some performance hits if you fill it to the point that it can't span the data over all 4 drives. so for example if you have 3 x 2tb drives and then a single 500gb drive you will hit a performance wall at the 1.5 tb mark when it starts to have to span 3 drives instead of 4. At that point the drobo will keep trying to move stuff around so that the 4 drive section is as full as it can be. So while you can mix drive sizes it is really beneficial to try to keep as much if not all of the data able to fit in the 4 drive span.
For another example lets go with having a 500gb, 1tb, 1.5tb and 2tb drive in the drobo.
The first 1.5 tb can fit in a 4 drive "strip" because it takes 500 gb (the smallest drive) and runs that across all 4 drives but uses one drive of space for the redundancy.
The next 1tb will be made of 500gb from each of the 1tb, 1.5b and 2tb drives with one 500gb chunk used for redundancy.
The next 500gb will be made of 500 gb from the 1.5 and the 2tb drive with the data mirrored between those chunks.
There will be 500 gb on the 2tb drive that is "reserved for future expansion" a nice way of saying lost because we can't protect it.
Now the drobo will try to fill the 4 drive slice first then the 3 drive then the 2 drive. Then in the background as you delete, move or change files the drobo will try to find data to fill in the lower levels with more drives as much as it can. While that processes is happening in the background it is still happening and using up cycles to do it. On the other hand if you just had 4 x 1tb drives you would always be in the sweet spot of writing to 4 drives and you wouldn't have the lost top end space. Now if you replace the 500gb drive in the above example with another 2tb drive you end up with something like this:
4 drive protection = (1tb x 4) - 1 tb for redundancy = 3tb of data
3 drive protection = (500 gb x3) - 500gb = 1tb of data
2 drive protection = (500gb x 2) - 500gb = 500gb of data
None lost to future expansion reservation for ~$150 from that original stair step configuration.
The drobo website is really bad at explaining the magic of Beyondraid they just go with a trust us approach and I tried to find a really good article that broke down the patent filing for the technology. But that was a failure. Here is one that gives examples etherealmind.com/drobo-how-beyond-raid-works/ and if you google for how beyondraid works.
To summarize:
With the 2nd gen enclosure you won't get enough better performance (or any really) by adding really expensive drives.
If you want better performance you probably want to get a newer enclosure with a faster processor.
You will get better performance by ensuring as much of your data is on a 4 drive slice as you can.
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No clue. I use 5400RPM drives in my Gen 2 Drobo. It's a little slow, but I bought it for redundancy not performance. I think the firmware itself is pretty slow though.
My only advice would be to consider the heat implications of 10k drives. Those get hot, and the Drobo is pretty tight in space. I would check the Drobo manual to see if there are any specs about heat.
My only advice would be to consider the heat implications of 10k drives. Those get hot, and the Drobo is pretty tight in space. I would check the Drobo manual to see if there are any specs about heat.
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Probably, since the faster the drives, the faster the Drobo can get the data. Just make sure you get faster drives for all the drives, not just 1 or 2, as that won't change anything.
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