Re: disabling write cache on SATA drives

[Christian Rice <xian@xxxxxxxxxxx>]

Perhaps no one else is using XFS as a root filesystem on SATA drives, 
but I've been giving it a go.  And I've been lucky to NOT experience a 
power failure in my machine room, I guess.

I've tried blktool and sdparm, both RPMS and compiled locally, but 
nothing can turn off the write cache.  I'm using multiple motherboards, 
different drive manufactureres, but no avail.

Has anyone had success with this issue?  Am I forced to continue on with 
PATA drives for the foreseeable future?

Any informed responses would be a huge help.


Details:
Tyan mobo, Opteron, 2.6.12-1.1398_FC4smp, x86_64, WDC WD800JD-00LS SATA 
drive
modules:
sata_sil               15301  4
libata                 58825  1 sata_sil
sd_mod                 25153  6
scsi_mod              167417  2 libata,sd_mod


nForce4 mobo, Athlon64 X2, 2.6.15-1.1831_FC4smp, x86_64, ST380817AS SATA 
drive
modules:
libata                 98265  1 sata_nv
sd_mod                 53697  2
scsi_mod              195321  2 libata,sd_mod



Christian Rice wrote:

> We all know that disabling write cache on drives with no battery 
> backup is a good thing, and we all know how to do it on  your average 
> IDE drive (hdparm -W0 /dev/hda).
>
> But what about on SATA disks?  I've found sdparm, which has settings 
> for disabling write cache on SCSI disks (and supposedly SATA disks 
> that use the SCSI device (eg, /dev/sda).  It simply doesn't work, though:
>
> [root@sqld xian]# sdparm --set WCE=1 /dev/sda
>    /dev/sda: ATA       Maxtor 7Y250M0    YAR5
> change_mode_page: failed setting page: Caching (SBC)
>
> [root@sqld xian]# uname -r
> 2.6.14-1.1656_FC4smp
>
> Of course I'm using XFS...
>
> The sdparm web page suggests some SCSI commands will be better 
> implemented in kernel 2.6.15.
>
> The only other thing I might try here is to recompile a 64-bit version 
> of sdparm, as I downloaded/installed version .96 i386, but this system 
> is a dual-proc Opteron running 64-bit FC4.
>
> Anyone have any other ideas?

On Mon, Jan 30, 2006 at 12:19:51PM -0800, Christian Rice wrote:

> > We all know that disabling write cache on drives with no battery backup 
> > is a good thing, and we all know how to do it on  your average IDE drive 
> > (hdparm -W0 /dev/hda).
> >
> > But what about on SATA disks?
>  

Is blktool the New(tm) way to do this?

-- Russell Howe | Why be just another cog in the machine, 
rhowe@xxxxxxxxxxxx | when you can be the spanner in the works?