Advanced disk format at WD20EARS: what should "camcontrol identify" show?

[Alexander Motin]

Hi.

On 04.04.2011 09:10, Lev Serebryakov wrote:
>      I'm replacing old WD500AAKS HDDs in my (software) RAID5 with new
> WD20EARS, which are advanced format. And speed is terrible. RAID5
> rebuilding shows about 8MiB/s (55MiB/s is typical speed for old AAKSes)...
>
>    I'm affraid, that my HDD is in some strange mode with 512 byte
> sectors emulation:
>
> ================
> blob# camcontrol identify /dev/ada5
> pass5:<WDC WD20EARS-00MVWB0 51.0AB51>  ATA-8 SATA 2.x device
> pass5: 300.000MB/s transfers (SATA 2.x, UDMA6, PIO 8192bytes)
>
> protocol              ATA/ATAPI-8 SATA 2.x
> device model          WDC WD20EARS-00MVWB0
> firmware revision     51.0AB51
> serial number         WD-WMAZA2743249
> WWN                   50014ee6ab72f596
> cylinders             16383
> heads                 16
> sectors/track         63
> sector size           logical 512, physical 512, offset 0
> LBA supported         268435455 sectors
> LBA48 supported       3907029168 sectors
> PIO supported         PIO4
> DMA supported         WDMA2 UDMA6
> ================
>
>    Should "camcontrol identify" shows "physical 4096" in "sector size"?
> Some Alexander Motin's posts to mailing lists says "yes", but I can not find what
> should I think (do) if it doesn't.

Unluckily present 4K driver don't usually honor specification in part of 
reporting physical sector sizes. I haven't seen supporting ones myself 
actually. So I wouldn't trust those 512/512/0 numbers.

>    It is 8-STABLE (after 8.2-RELEASE) system. RAID stripes are 128KiB,
> and RAID is built from whole drives (no partitions), so, write
> requests should not be misaligned.

At least first 4K WD disks had a jumper to add offset of 63 sectors. 
Make sure that you don't have one set.

-- 
Alexander Motin