Am 02.07.2011 23:30, schrieb Drew: >> I thought that I had read the TLER was not useful for mdraid, so that >> enterprise drives were not really advised for mdraid. Am I wrong about >> this? > > TLER just shortens the firmware's error recovery from something like > 60 seconds down to 4 seconds. It's mainly useful in hardware RAID but > I can see it being useful with mdraid in the enterprise where you > can't afford to wait for the drive to do it's own recovery attempts. > > This is not correct. You may want to read the ATA8-ACS2 draft standard (see www.t13.org). There you'll find: SCT-ERC The internal error recovery procedure includes a vast amount of algorithms. If a disk cannot read a sector and starts error recovery, it may take far more than a minute. With ERC you can tell the disk beforehand to stop processing the command (may it be "read" or "write") and return a "uncorrectable error" to the host. Some drives (i.E. recent Hitachi Deskstar, which I do recommend!) do not allow you to set ERC lower than 6.5s. For a home-box I recommend adding a startup-script and a hotplug-script (as ERC-settings get reset to firmware defaults upon power-on) which uses smartmontools >=5.41 to set the read-ERC to 7s and the write ERC to 12s. We have good experience that this works out well in productive systems. /Stefan P.S.: pseudo-knowledge makes important things go really badly wrong. -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
