Hi. I wanted to know how was my HD set, and I was issuing information-querying commands like hdparm /dev/hda, hdparm -i /dev/hda when I accidentally issued hdparm -X /dev/hda (idiot me). The hdparm man page does not tell what happens when the -X option is used without an argument. I suspect it is equal to using an argument of 0; the man page says "Setting 00 restores the drive´s "default" PIO mode, and 01 disables IORDY"
The output of the hdparm -X /dev/hda command mentioned something about IORDY. I then issued hdparm -i /dev/hda and the output said the drive was still in UDMA5. Good sign! Maybe the command did nothing. To be sure, I issued hdparm -X 69 /dev/hda (to set the mode to UDMA5), and issued another hdparm -i /dev/hda (the output seemed identical). I checked dmesg, and I saw at the end one message saying that the mode had been set to UDMA-100 (which is UDMA5 I believe). This is good: this message was probably generated by the hdparm -X 69 /dev/hda command, so the earlier hdparm -X /dev/hda command must have generated no messages, which suggests it did nothing. I then shut the computer down and I writing this from a liveCD. I do not even want to access the disk read only without knowing I have not messed up. So: does anybody know if hdparm -X /dev/hda is safe (on a running system...)? Thank you -- Software is like sex: it is better when it is free - Linus Torvalds
