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

Lev Serebryakov lev at FreeBSD.org
Mon Apr 4 06:10:43 UTC 2011


Hello, Alexander.

    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.

  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.


-- 
// Black Lion AKA Lev Serebryakov <lev at FreeBSD.org>



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