--- In firebird-support@yahoogroups.com, "Fabrice Aeschbacher"
<fabrice.aeschbacher@...> wrote:

>
> > > > <SL> Have you disabled all OS write caching features for the
> HDDs?
> > > No. Should we?
> >
> > Yes, always!
> >
> > The only write caching which should be enabled is at the

hardware

> level,
> > when you have a RAID controller with a battery backup module.
> >
> > This type of caching is hidden from the OS.

In fact, it seams that our hard disks does not support write caching:

# hdparm -I /dev/hdc

/dev/hdc:

ATAPI CD-ROM, with removable media
Model Number: HL-DT-STDVD-ROM GDR8163B
Serial Number:
Firmware Revision: 0F15
Standards:
Likely used CD-ROM ATAPI-1
Configuration:
DRQ response: 50us.
Packet size: 12 bytes
Capabilities:
LBA, IORDY(can be disabled)
DMA: sdma0 sdma1 sdma2 mdma0 mdma1 mdma2 udma0 udma1 *udma2
Cycle time: min=120ns recommended=120ns
PIO: pio0 pio1 pio2 pio3 pio4
Cycle time: no flow control=120ns IORDY flow
control=120ns
Commands/features:
Enabled Supported:
* NOP cmd
* DEVICE RESET cmd
* PACKET command feature set
* Power Management feature set
* Automatic Acoustic Management feature set
HW reset results:
CBLID- below Vih
Device num = 1


And when trying to disable:

# hdparm -W0 /dev/hdc

/dev/hdc:
setting drive write-caching to 0 (off)
HDIO_DRIVE_CMD(setcache) failed: Input/output error



Fabrice