Timothy Murphy wrote: >> Check your bios, and make sure that you did not have IDE mode enabled and >> AHCI is selected . > > Thanks for your response, and for the others received. > > But I should have pointed out that the slow operation > has only started recently, in the last week or so, > after working normally since I acquired the disk a year or so ago. To add to the mystery, I just checked with hdparm, and the speed of the disk (as measured this way) seems normal, compared with various other disks: ----------------------------------- The "slow disk" [tim at helen ~]$ sudo hdparm -t /dev/sdb /dev/sdb: Timing buffered disk reads: 168 MB in 3.00 seconds = 55.98 MB/sec ----------------------------------- Another disk on the same machine [tim at blanche ~]$ sudo hdparm -t /dev/sda /dev/sda: Timing buffered disk reads: 146 MB in 3.01 seconds = 48.57 MB/sec ----------------------------------- An external hard disk attached to the same machine [tim at helen ~]$ sudo hdparm -t /dev/sdc /dev/sdc: Timing buffered disk reads: 54 MB in 3.03 seconds = 17.80 MB/sec ----------------------------------- I have Windows XP on another partition. I don't think I've ever used it (I always install Windows if it is not already on the machine, as I've had a couple of occasions when it has saved my life). I'll see how fast (or slow) Windows backup goes. -- Timothy Murphy e-mail: gayleard /at/ eircom.net tel: +353-86-2336090, +353-1-2842366 s-mail: School of Mathematics, Trinity College Dublin