[CentOS] Is ext4 safe for a production server?

Jussi Hirvi listmember at greenspot.fi
Fri Dec 11 14:52:23 UTC 2009

Centos 5.x, ext3, md raid1

As I do not have UPS for all machines, and I most often use md raid 
(level 1), I would like to turn the write cache off for all of my server 
discs. But how?

Below is what I have already found out:

On the page


I read that I could do this by running
	hdparm -W0 /dev/sdX
, but when I say
	hdparm -h,
it says that the -W option is “dangerous”.

This is the current hdparm output for one of my raid discs:

[root at mail etc]# hdparm /dev/sda
  IO_support   =  0 (default 16-bit)
  readonly     =  0 (off)
  readahead    = 256 (on)
  geometry     = 38913/255/63, sectors = 625142448, start = 0

(BTW, here is a hdparm tutorial for Ubuntu:


And when I get this done, then how can I make the setting last over the 
next bootup?

P.S. Do you really have to quote the whole thread when you respond?

Jussi Hirvi * Green Spot
Topeliuksenkatu 15 C * 00250 Helsinki * Finland
Tel. +358 9 493 981 * Mobile +358 40 771 2098 (only sms)
jussi.hirvi at greenspot.fi * http://www.greenspot.fi

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