Western Digital WD20EARS "Advanced Format" - 4k sectors needed

Question

I just purchased a Western Digital WD20EARS which uses "Advanced Format" which to my understanding are 4k sectors rather than 512 byte sectors.  To function properly, the partitions need to align with this 4k sector size - like an SSD?  Anyway, I found the following references, but wanted to ask here too before I attempt partitioning the hdd: what is the proper process and software to ensure that I do this correctly?
* This post talks about using parted from the shell for the partitioning.
* I've also read in various places to simply start the partition with fdisk in sector mode (hitting 'u') and be sure to start at sector 64 rather than on sector 63.  Example.  Example 2 (you have to search for the keyword 'linux')
* I've also read to do the same, except to start at sector 2048.
* This post at the centos forum recommends using 'fdisk -H 224 -S 56 /dev/sdX' to "make sure that all possible partitions will be in alignment with the 4K sectors. Any partition you create that way will align the partition with the 4K sectors."
Thanks in advance for any info.
EDIT:  https://wiki.archlinux.org/index.php/Advanced_Format
Last edited by graysky (2011-08-31 13:12:05)

Answer 1

I just used fdisk (setting both modes 'c' and 'u') and aligned it to sector 2048 - interestingly, in sector mode, the default starting point is not 63 or 64 but 2048 in the current version of fdisk (2.17.2) so it's automatically taking care of the 4k sector size for me.  Everything works fast so I'm assuming that it's correct.
Credit to this post.
Here are some reference numbers on three drives
a = Seagate 7200.12 ST31000528AS (1.0 TB) spinning at 7200 RPM
b = WD Black WD1001FALS (1.0 TB) spinning at 7200 RPM
c = WD Green WD20EARS (2.0 TB) spinning at 5900 RPM
# hdparm -Tt /dev/sd[a-c]
/dev/sda:
Timing cached reads: 15512 MB in 1.99 seconds = 7780.21 MB/sec
Timing buffered disk reads: 338 MB in 3.02 seconds = 112.07 MB/sec
/dev/sdb:
Timing cached reads: 15796 MB in 1.99 seconds = 7922.77 MB/sec
Timing buffered disk reads: 308 MB in 3.01 seconds = 102.20 MB/sec
/dev/sdc:
Timing cached reads: 15128 MB in 1.99 seconds = 7586.77 MB/sec
Timing buffered disk reads: 356 MB in 3.01 seconds = 118.08 MB/sec
Not too bad considering the WD20EARS spins ~18 % slower than the other two.
EDIT: This drive also attempts to part the read heads once every 8 seconds which is just horrible.  Use hdparm in your /etc/rc.local to disable this 'feature' and likely add life to your hdd:
# echo "hdparm -S 242 /dev/sdX" > /etc/rc.local
EDIT2: Here is a trivial script that detects the presence of this drive on my system and automatically send that hdparm command.  Note that I only have a WD20EARS and this script won't work for multiple copies.
#!/bin/bash
test=`fdisk -l | grep 2000.4 | cut -c13-13`
if [ -z "$test" ]; then
echo retarded drive not found, exiting
exit 0
else
echo retarded drive found, fixing lcc
hdparm -S 242 /dev/sd$test
fi
Last edited by graysky (2010-06-27 06:58:30)