Third-party drives not permitted on Gen 11 servers

Stroller stroller at stellar.eclipse.co.uk
Mon Feb 8 13:08:54 CST 2010


On 8 Feb 2010, at 11:48, Tim Small wrote:
> ... it's possible that there are genuine
> reasons for this - I spent/wasted most of last week diagnosing what is
> starting to look like a firmware bug on WD 2TB "green power" drives  
> on a
> non-Dell server ...
>
> I wouldn't be surprised if the H700 adaptor firmwares are doing  
> various
> "unusual" things to the hard drives, and it's possible that Dell has  
> got
> nervous about buggy firmware from unqualified drives reflecting  
> badly on
> their hardware.....

There's a thread on gentoo-user which I have just now seen come to  
conclusions regarding modern drives with 4K sector sizes ("1-Terabyte  
drives - 4K sector sizes? -> bar  performance so far")

It appears that AIUI fdisk will, by default, create partitions out of  
optimal alignment for these modern drives. My understanding of this is  
a little sketchy - I *think* I'm understanding correctly, but I beg  
forgiveness if I explain wrong.

The first partition created by fdisk will, by default, start at sector  
63, as shown by `echo p | sudo fdisk -u /dev/sdb`. Two users in that  
thread report that creating the partition manually to start at sector  
64 will, on large modern drives with 4K sector sizes, increase  
performance by a couple of orders of magnitude, "to roughly 20 seconds  
from 8-10 minutes".

I believe cfdisk may also by default create its first partition  
beginning at sector 63, as I'm seeing that on one of my systems here  
and I tend to use cfdisk for partitioning.

Apparently Windows, since Vista, at least, does not suffer this  
problem, and already aligns partitions optimally by default.

So it would be quite cool if Dell's firmware specially compensated for  
this for the benefit of Linux users. If this were the reason (and  
actually I suspect that it is not) then the firmware should squawk  
about 3rd-party drives, rather than rejecting them outright, as  
already agreed by everyone posting to this thread.

Stroller.



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