Building a RAID 5 Array, is this a good controller for the price?

[Boon]

Hi guys and gals,

 

 

I'm planning to build a RAID 5 array and I am halfway down the track with parts, however I am a bit stuck on what kind of RAID controller card to go with. One that is affordable that is >.<

Just for background info, the array will be 3x 4TB drives to start with, possibly expanding in the future.

 

I have read quite a few reviews which mostly mention LSI being one of the best in the business, however they are very hard to snag for a low price. Also Areca are very renowned by most reviews I have seen. I am also considering Adaptec, however I have seen that their performance can degrade quite significantly over their life. Then again, I don't really know what factors contribute to this degrading either. Any who....

 

I am really aiming to score a card for less than $350, new or second hand doesn't bother me. 

 

I have seen this card listed on ebay for about $150 in working condition, second hand; however I thought that I would open this up for debate before I commit to buying any card.

 

http://globalsp.ts.fujitsu.com/dmsp/Publications/public/ds-py-raid-56-6G-D2616.pdf

 

I am interested in the fact that the card is based on LSI, or would this not really correlate to any higher performance/quality? Looks similar to the LSI 9260 8i, but is it capable of a similar performance?

 

Also, is there any advantage to having an upgradable cache either?

 

 

Thanks in advance (:

[MrBucket101]

raid 5 is statistically illogical at sizes of 12TB and above. The probability of a bad sector occurring in a different drive after one drive has died, is something in the range of 7-12% IIRC...meaning it will fail to rebuild the array

You'll be fine at first, but as soon as you add an additional drive, you'll be flirting with disaster.

 

use raid 6 when you're > 12TB

 

I have the LSI 9260-8i and I'm extremely happy with it. 

[wpirobotbuilder]

http://globalsp.ts.fujitsu.com/dmsp/Publications/public/ds-py-raid-56-6G-D2616.pdf

 

I am interested in the fact that the card is based on LSI, or would this not really correlate to any higher performance/quality? Looks similar to the LSI 9260 8i, but is it capable of a similar performance?

The LSI controller that the card uses is the exact same one as in the 9260-8i. That controller is the LSI SAS2108, so it should perform almost identically.

 

Also, is there any advantage to having an upgradable cache either?

 

Upgradeable cache isn't as important as having a cache at all, don't worry about it.

 

I'm planning to build a RAID 5 array and I am halfway down the track with parts, however I am a bit stuck on what kind of RAID controller card to go with. One that is affordable that is >.<

Just for background info, the array will be 3x 4TB drives to start with, possibly expanding in the future.

 

raid 5 is statistically illogical at sizes of 12TB and above. The probability of a bad sector occurring in a different drive after one drive has died, is something in the range of 7-12% IIRC...meaning it will fail to rebuild the array

You'll be fine at first, but as soon as you add an additional drive, you'll be flirting with disaster.

 

use raid 6 when you're >= 12TB

 

If you use NAS optimized drives (WD Red or Seagate NAS) you won't have to worry as much about RAID failures as you would with non-NAS drives. That said, for large arrays you should be using either RAID 10 or RAID 6, because rebuilds take a long time.

 

I recommend RAID 10, because rebuilds go incredibly fast and you only have to rebuild one drive, rather than calculating parity for every sector in the array. The downside is the space-efficiency.

[MrBucket101]

 

If you use NAS optimized drives (WD Red or Seagate NAS) you won't have to worry as much about RAID failures as you would with non-NAS drives.

 

In the situation described above, NAS drive or not, there is still a high percentage of failure to rebuild. This is due to the sector count at that size, and the percentage of probability that a single sector residing elsewhere will be bad. While it is true that a NAS optimized drive, will mitigate the likelihood of a drive failure, it doesn't eliminate it. 

 

[Boon]

Thanks for all of the insight guys, I am taking all of this into account before I go ahead with my choices.

 

The LSI controller that the card uses is the exact same one as in the 9260-8i. That controller is the LSI SAS2108, so it should perform almost identically.

 

I have the LSI 9260-8i and I'm extremely happy with it. 

 

I may be possibly buying a 9260-8i from a friend, however it is good to know that the Fujitsu card should perform similar if I do need one.

 

If you use NAS optimized drives (WD Red or Seagate NAS) you won't have to worry as much about RAID failures as you would with non-NAS drives. That said, for large arrays you should be using either RAID 10 or RAID 6, because rebuilds take a long time.

 

I recommend RAID 10, because rebuilds go incredibly fast and you only have to rebuild one drive, rather than calculating parity for every sector in the array. The downside is the space-efficiency.

 

raid 5 is statistically illogical at sizes of 12TB and above. The probability of a bad sector occurring in a different drive after one drive has died, is something in the range of 7-12% IIRC...meaning it will fail to rebuild the array

You'll be fine at first, but as soon as you add an additional drive, you'll be flirting with disaster.

 

use raid 6 when you're >= 12TB

 

I am really aiming to maximise the space I can get from the drives. Is there a possibility of going RAID 50 in this case? or should i sacrifice the performance for fault tolerance and just go RAID 6?

I have personally gone with the 4tb platters as I have heard that these platters perform better than 2 and 3tb. Is this true or just a myth   I will be open to changing the number of drives I buy if a different RAID level is used.

 

Also I am considering buying Hitachi NAS drives as opposed to WD or Seagate. Would their lower failure rate offer any kind of extra inherent fault tolerance due their reputation of being very reliable? or am I just rolling the dice too much with this one here....

 

 

 

Once again, thanks a heap for your help. I really appreciate your advice on this one

[Shaqalac]

Are you going to run with a hardware RAID solution?

If you prefer a software solution you could grab a LSI 9211-8i at $99 and flash it to IT-mode with alpenwasser's guide.

I've been following this guide twice and if you don't have a bricked card from the very beginning it is done in 15 minutes time.

[MrBucket101]

Thanks for all of the insight guys, I am taking all of this into account before I go ahead with my choices.

 

 

 

I may be possibly buying a 9260-8i from a friend, however it is good to know that the Fujitsu card should perform similar if I do need one.

 

 

 

I am really aiming to maximise the space I can get from the drives. Is there a possibility of going RAID 50 in this case? or should i sacrifice the performance for fault tolerance and just go RAID 6?

I have personally gone with the 4tb platters as I have heard that these platters perform better than 2 and 3tb. Is this true or just a myth   I will be open to changing the number of drives I buy if a different RAID level is used.

 

Also I am considering buying Hitachi NAS drives as opposed to WD or Seagate. Would their lower failure rate offer any kind of extra inherent fault tolerance due their reputation of being very reliable? or am I just rolling the dice too much with this one here....

 

 

 

Once again, thanks a heap for your help. I really appreciate your advice on this one

Take a look at the 10TB+ storage thread. http://linustechtips.com/main/topic/21948-ltt-10tb-storage-show-off-topic/

 

25% of us on the list are using RAID 6

To me, Raid 50 doesn't seem as beneficial as RAID 6. Say you set up 2 RAID 5's, 3 disks each, then you use RAID 0 and join the 2 RAID 5's. If 2 disks on one of the individual RAID 5's fail, then you lose the entire array. Wheras with RAID 6, you can lose 2 drives, and still maintain the data integrity. You just can't lose a third disk.

 

With RAID 50, I also don't think you will be able to expand the array like you mentioned in the first post.

I haven't done any googling, just some thoughts of mine, if it turns out I'm wrong don't hold it against me

[Boon]

Are you going to run with a hardware RAID solution?

If you prefer a software solution you could grab a LSI 9211-8i at $99 and flash it to IT-mode with alpenwasser's guide.

I've been following this guide twice and if you don't have a bricked card from the very beginning it is done in 15 minutes time.

 

I am going for a Hardware RAID controller in this case.

 

Thanks for the info though!