FUA and DPO unsupported using sata_nv on MCP55?

FUA and DPO unsupported using sata_nv on MCP55?

[Eamonn Hamilton]

Hi,

I've got a couple of Samsung HD501LJ drives attached to a KN9 Ultra
board using the MCp55 chipset, and I'm getting an NCQ depth of 0
reported at boot, which as I understand it is because support for NCQ
isn't in the sata_nv driver yet for this chipset.

ata1.00: ATA-7, max UDMA7, 976773168 sectors: LBA48 NCQ (depth 0/32)
ata2.00: ATA-7, max UDMA7, 976773168 sectors: LBA48 NCQ (depth 0/32)

Later in the boot, however, I get 
SCSI device sda: write cache: enabled, read cache: enabled, doesn't
support DPO or FUA
SCSI device sda: write cache: enabled, read cache: enabled, doesn't
support DPO or FUA

which as I understand it means my data ( plus the wifes picture
archive! ) is at risk, as I have write cache enabled and barrier support
is disabled because of the lack of FUA. Is this caused by my drives, or
is there something I need to enable?

Any hints gratefully received,
Eamonn

-- 
Eamonn Hamilton <eamonn.hamilton@saic.com>


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Re: FUA and DPO unsupported using sata_nv on MCP55?

[Tejun Heo]

Eamonn Hamilton wrote:
> Hi,
> 
> I've got a couple of Samsung HD501LJ drives attached to a KN9 Ultra
> board using the MCp55 chipset, and I'm getting an NCQ depth of 0
> reported at boot, which as I understand it is because support for NCQ
> isn't in the sata_nv driver yet for this chipset.
> 
> ata1.00: ATA-7, max UDMA7, 976773168 sectors: LBA48 NCQ (depth 0/32)
> ata2.00: ATA-7, max UDMA7, 976773168 sectors: LBA48 NCQ (depth 0/32)

Yeap.

> Later in the boot, however, I get 
> SCSI device sda: write cache: enabled, read cache: enabled, doesn't
> support DPO or FUA
> SCSI device sda: write cache: enabled, read cache: enabled, doesn't
> support DPO or FUA
> 
> which as I understand it means my data ( plus the wifes picture
> archive! ) is at risk, as I have write cache enabled and barrier support
> is disabled because of the lack of FUA. Is this caused by my drives, or
> is there something I need to enable?

Nothing is in danger.  FUA just speeds up barrier a tad bit.  Doesn't
matter really.

-- 
tejun

Re: FUA and DPO unsupported using sata_nv on MCP55?

[Eamonn Hamilton]

Hi,

I'm glad to hear that my data is looking safe, although my XFS
filesystem reports "Disabling barriers, not supported by underlying
device" when I try to mount a RAID-1 of these two disks. I guess it's
something to do with the software raid code?

Anyway, thanks for the help, it's always a pleasure :)

Oh, I don't suppose anybody has any idea when the NCQ support might go
into the sata_nv driver? I seem to recall it was being talked about
months ago?

Cheers,
Eamonn


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