Archives For November 30, 1999

Ubuntu Prevent Data Loss
This simple tutorial is going to show you how to disable disk write caching in Ubuntu to prevent data loss when you may experience power failure.

Enable write caching improves disk performance, but a power outage or equipment failure might result in data loss or corruption. It’s recommended only for disks with a backup power supply.

Some third-party programs require disk write caching to be enabled or disabled. If your disk are used for Event Store databases, it’s highly recommended to disable disk caching to help ensure that data is durable when the machine might experience a power, device or system failure.

In Ubuntu, it’s easy to check out whether disk caching is enabled on your disk or not by running below command:

sudo hdparm -i /dev/sda

Replace /dev/sda with your device and you’ll see below similar outputs:

Model=WDC WD3200BPVT-22JJ5T0, FwRev=01.01A01, SerialNo=WD-WX61EC1KZK99
Config={ HardSect NotMFM HdSw>15uSec SpinMotCtl Fixed DTR>5Mbs FmtGapReq }
RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=50
BuffType=unknown, BuffSize=8192kB, MaxMultSect=16, MultSect=off
CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=625142448
IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120}
PIO modes: pio0 pio3 pio4
DMA modes: mdma0 mdma1 mdma2
UDMA modes: udma0 udma1 udma2 udma3 udma4 udma5 *udma6
AdvancedPM=yes: unknown setting WriteCache=enabled
Drive conforms to: Unspecified: ATA/ATAPI-1,2,3,4,5,6,7

* signifies the current active mode

The words in red, WriteCache=enabled, means caching is enabled! To disable it, edit the “/etc/hdparm.conf” with your favorite editor, here I use vi as example:

sudo vi /etc/hdparm.conf

Uncomment the line “#write_cache = off” (without quotes) by removing the # at its beginning. So it looks like:

# -W Disable/enable the IDE drive’s write-caching feature
write_cache = off

After that, restart your computer and check out the write caching status again to make sure it’s disabled.