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We recently purchased a number of 3TB drives, only to realize later it was for a server running a Perc 6i, and that >2TB drives are not supported. Based on the amount we paid though, the restocking fee along with the cost of the 2TB drives is about the same.

All the questions here and on Google address that the Perc 5i and 6i controllers cannot recognize greater than 2TB hard drives. Dell has this to say: "NO earlier controllers, such as the PERC4/5/6, SAS5/6 (or ANY other Dell controller not mentioned) have this support and in some cases, even though you may be able to see the drive, this has NOT been tested or validated, so possible data loss could be experienced."

However, if we format the 3TB drives as 2TB drives on the Perc controller and put them in an array (that is, not use them as 3TB drives at all), are there issues we will run into in terms of reliability, data integrity or MTBF? Or is it like putting more than 4 gigs of RAM in a 32 bit OS, that there is more storage but it just isn't accessible.

Thanks

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I think the statement from Dell "NO earlier controllers, such as the PERC4/5/6, SAS5/6 (or ANY other Dell controller not mentioned) have this support and in some cases, even though you may be able to see the drive, this has NOT been tested or validated, so possible data loss could be experienced." says it all. Proceed at your own risk. –  joeqwerty Oct 31 '12 at 15:28
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3 Answers

up vote 5 down vote accepted

In my experience, it's like putting more than 4 GB or RAM into a 32 bit OS, in that the additional space is simply not usable.

There is one major difference though, in that if you have support through Dell, and you use unsupported hardware (like a 3 TB drive), you will be invalidating your support, and may very well be told "no" if you need to call in about a an issue related to the PERC card, storage array or drives (and most anything can be stretched into being "related" to those components, if they want to badly enough).

It would really be best to just replace the 3TB drives with 2TB ones. Yeah, the price is about the same, but if you're not going to be able to use the additional TB of disk space, the only functional difference is that one's supported, and one is unsupported and "has NOT been tested or validated, so possible data loss could be experienced." The better choice is clearly the supported one that's otherwise functionally identical to the unsupported one.

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For the controllers you mentioned, 3TB drives are not support by their firmware. I don't see how you can format the 3TB drives as 2TB drives on the Perc controller and put them in an array (that is, not use them as 3TB drives at all).

If the controllers don't support drives that large, you aren't going to be able to do that!

Formatting is something that happens at the file system level. You first need to connect the drives to the controller and initialise them (sometimes not always, vendor specific), then assign the physical disk drives to virtual disks. You assign whole physical disks to virtual disks, you can't assign chunks at this point. (Also

You only work with less than $total-PD-size if you have created a virtual disk that is smaller than the size of it's single physical disk place of residence, or if the virtual disks spans multiple drives but is still smaller than the size on one singe member physical disk, or by creating less than whole disks partitions on top of virtual disks.

You are dancing with the devil here I feel, if you can get a refund for the drives and get 2TB disks. Alternatively change the Perc controllers if you can from something else like a H200 or H700 if either of those support 3TB drives. Either way, do it the right way.

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Can you elaborate on "Formatting is something that happens on top of a file system"? –  Andrey Vihrov Oct 31 '12 at 19:46
    
@AndreyVihrov Whoops, my mistake, corrected. Thanks :) –  jwbensley Nov 1 '12 at 9:15
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I have been using 3TB drives in my PERC 6i servers for quite a while. They work great and you gain about 400 gb over using 2TB drives due to formatting. I use them in a raid 5 array, so 3 drives create exactly a 4TB array. If I was using 2TB drives, i would get about 3.6TB in the formatted array. Remember, the limit is 2.2TB, so i gain a small percentage. Being that the 3TB drives are pretty much the same price, it works out very nicely for me. I have had no issues. It would be nice if dell would update the firmware, but this is dell we are talking about. They just want us to buy new parts instead of making the old ones even better.

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