Support for WD Advanced Format disks

[Ilya Bakulin]

On Sat, 28 Aug 2010 13:09:12 +0400
Ilya Bakulin <webmaster at kibab.com> wrote:

> Right now I'm running phybs -w /dev/ad7p1

Well, phybs finished.
Results:
kibab-desktop# ./phybs -w /dev/ad7p1
   count    size  offset    step        msec     tps    kBps

  131072    1024       0    4096     3098125       0      42
  131072    1024     512    4096     3100047       0      42

   65536    2048       0    8192     1505809       0      87
   65536    2048     512    8192     1505179       0      87
   65536    2048    1024    8192     1506127       0      87

   32768    4096       0   16384     1522343       1      86
   32768    4096     512   16384     1521017       1      86
   32768    4096    1024   16384     1523748       1      86
   32768    4096    2048   16384     1522853       1      86

   16384    8192       0   32768      890911       3     147
   16384    8192     512   32768      892026       3     146
   16384    8192    1024   32768      890699       3     147
   16384    8192    2048   32768      891862       3     146
   16384    8192    4096   32768      889903       3     147

Obviously 34-sectors offset is bad for phybs. Write requests are NEVER get aligned.
I have recreated partition as follows:

kibab-desktop# gpart delete -i 1 ad7
ad7p1 deleted
kibab-desktop# gpart add -t freebsd-ufs -s 10G -b 63 ad7
ad7p1 added
kibab-desktop# gpart show ad7
=>        34  2930277101  ad7  GPT  (1.4T)
          34          29       - free -  (15K)
          63    20971520    1  freebsd-ufs  (10G)
    20971583  2909305552       - free -  (1.4T)

So, we have ad7p1 which is still misaligned, but if write request will start at offset=512, it will be aligned properly.
Let's test as follows:

kibab-desktop# ./phybs -l 4096 -w /dev/ad7p1
   count    size  offset    step        msec     tps    kBps

   32768    4096       0   16384     1520609       1      86
   32768    4096     512   16384       17898     151    7323
   32768    4096    1024   16384     1524899       1      85

:-) Aligned writes are 86 times faster than misaligned!!!
-- 
Regards,
Ilya Bakulin
http://kibab.com
xmpp://kibab612@jabber.ru
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