On 07/27/2011 11:36 AM, Tom H wrote:
On Wed, Jul 27, 2011 at 12:30 AM, Yasha Karant<[email protected]> wrote:
For reasons that are irrelevant to this discussion, we have ended up with a
number of new workstations with WD Advanced Format "green" 1.5 TByte drives.
We have been experiencing a number of difficulties that had to do with
partition boundaries, etc. After a bit of digging, I found:
http://community.wdc.com/t5/Desktop/Problem-with-WD-Advanced-Format-drive-in-LINUX-WD15EARS/td-p/6395
Is anyone using a WD Advanced Format drive with SL 6? We are not and
probably will/can not use LVM, but rather standard ext 2, 3, or 4
partitions, included the extended partition model.
If you are using this type of drive, information on the specifics of the
formatting command(s) and syntax to use these WD drives would be
appreciated. Any link to a detailed document or URL would be appreciated.
For SSDs but relevant for "regular" disk partition alignment too:
http://www.linuxfoundation.org/news-media/blogs/browse/2009/02/aligning-filesystems-ssd%E2%80%99s-erase-block-size
The most relevant part of the article referenced in the above URL is:
However, with SSD’s (remember SSD’s? This is a blog post about SSD’s…)
you need to align partitions on at least 128k boundaries for maximum
efficiency. The best way to do this that I’ve found is to use 224
(32*7) heads and 56 (8*7) sectors/track. This results in 12544 (or
256*49) sectors/cylinder, so that each cylinder is 49*128k. You can do
this by doing starting fdisk with the following options when first
partitioning the SSD:
# fdisk -H 224 -S 56 /dev/sdb
end quote.
Assuming that WD is true to the semi-technical specifications it
provides, 4096 byte physical sectors, what should one use for the number
of heads (switch H above) and the number of sectors/track (switch S above)?
Note that it appears that in terms of the IDEMA Long Data Sector
Committee Advanced Format standard, the 512e (512 byte block emulation)
firmware on this Western Digital drive is defective or the issue would
not arise.
Yasha Karant
