Checking physical sector size of disks on Solaris

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Thursday, February 17. 2011

Checking physical sector size of disks on Solaris

I have just written a small onefifty-liner to check the physical block size of disk devices on Solaris. I have done this to show that the WD20EARS does indeed (erroneously!) report a physical sector size of 512 bytes.

See: blocksize.c (Source) and blocksize (binary, compiled on Solaris 10/x86).

Note that on the x86 platform, this will only work if the disks are attached to the sd driver (because the DKIOCGMEDIAINFOEXT ioctl is implemented only there and not in the cmdk driver). This will be the case if you use an AHCI controller supported by ahci(7d).

In my case (this is on 5.10 Generic_142910-17)

root@ilbirs> format -e </dev/null | egrep "[0-9]\."
0. c0t0d0 <DEFAULT cyl 30390 alt 2 hd 255 sec 63>
1. c0t1d0 <ATA-Hitachi HDS72107-A70M-698.64GB>
2. c0t3d0 <ATA-WDC WD20EARS-00M-AB50-1.82TB>
3. c0t4d0 <ATA-Hitachi HDS72107-A70M-698.64GB>

root@ilbirs> ./blocksize /dev/rdsk/c0t3d0
dkmp.dki_capacity = 3907029167
dkmp.dki_lbsize = 512
dkmp_ext.dki_capacity = 3907029167
dkmp_ext.dki_lbsize = 512
dkmp_ext.dki_pbsize = 512
root@ilbirs> ./blocksize /dev/rdsk/c0t4d0
dkmp.dki_capacity = 1465149167
dkmp.dki_lbsize = 512
dkmp_ext.dki_capacity = 1465149167
dkmp_ext.dki_lbsize = 512
dkmp_ext.dki_pbsize = 512

The above WD20EARS is revision "00MVWB0". I have another one at revision "00J2GB0", unfortunately hanging on a controller unsupported by ahci(7d).

If anybody has a WDxxEARS correctly reporting a dki_pbsize = 4096, I would love to hear it.

Edit:
If anybody has a Samsung HD204UI, I would also like to know if this disk correctly reports the physical block size.
in Solaris at 08:48
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Nice utility. Samsung HD204UI as requested:


1. c10t9d1 < ATA-SAMSUNG HD204UI-0001-1.82TB >
/pci@0,0/pci15ad,7a0@15,1/pci1014,3b1@0/sd@9,1

root@tank:~# ./blocksize /dev/rdsk/c10t9d1
dkmp.dki_capacity = 3907029168
dkmp.dki_lbsize = 512
dkmp_ext.dki_capacity = 3907029168
dkmp_ext.dki_lbsize = 512
dkmp_ext.dki_pbsize = 512
#1 apnar on 2011-02-20 23:58
So there is a jumper (7-8) on the WD20EADS to turn on 4k blocks, even with the jump installed, I still get:

root@media:~# ./blocksize /dev/rdsk/c9t3d0
dkmp.dki_capacity = 3907029168
dkmp.dki_lbsize = 512
dkmp_ext.dki_capacity = 3907029168
dkmp_ext.dki_lbsize = 512
dkmp_ext.dki_pbsize = 512

Since I didn't know about the jumper setting before I installed the drives, I am resilvering my raidz now one drive at a time. I'll report any improvements in performance.
#2 cfs on 2011-07-11 20:42
Was that a typo? The WD20EADS is a pure, genuine 512 byte/sector drive. It is the similar WD20EARS which has 4096 bytes/sector.
#2.1 Christian Kühnke on 2011-07-11 20:55
In your code I think you may have a typo... your lbsize and pbsize are calling out the same thing:


printf ("dkmp_ext.dki_capacity = %llu\n", dkmp_ext.dki_capacity);
printf ("dkmp_ext.dki_lbsize = %u\n", dkmp_ext.dki_lbsize);
printf ("dkmp_ext.dki_pbsize = %u\n", dkmp_ext.dki_lbsize);


shouldn't the second line look like this?:


printf ("dkmp_ext.dki_pbsize = %u\n", dkmp_ext.dki_pbsize);
#3 Dean on 2011-12-07 16:20
Oh my, how embarassing is that (for me)!?

You are absolutely right. Will fix this tomorrow for the downloadable file.

Thanks!
#3.1 Christian Kühnke on 2011-12-07 23:15
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