I have two identical 9 gig scsi hard drives that I am trying to establish a mirror on my Windows NT 4.0 Server. Disk 0 has two partitions (C: and D:) and 16 megs of free space (This how the previous administrator set it up). Disk 1 shows up as free space in Disk Administrator. When trying to establish the mirror I am getting an error that there is not enough disk space on disk 1 to establish the mirror; yet they show the exact amount of space in the left hand margin in disk administrator. There is no compression set up on either disk. I can't figure out why the mirror isn't being established. Any thoughts?

Are the partitions all the same format? NTFS, fat?

No, one partition is FAT, and other is NTFS (disk 0). Disk 1 is just set up as free space.

This is from the help menu in disk adminTo format a partition and label the volume 1 On the Partition menu, click Commit Changes Now , and then click Yes to save the changes. 2 Click OK when Disk Administrator informs you that the disks were updated successfully and advises you to create a new Emergency Repair Disk. 3 Select the newly created partition. 4 On the Tools menu, click Format. 5 In the Format dialog box, select a file system, and then optionally specify the following: To name the partition, type a name in Volume Label. To skip scanning for bad sectors in the partition during formatting, click Quick Format. This option is not available when formatting mirror sets and stripe sets with parity. To compress the folders and files that are added to the volume, click Enable Compression. This option is available if the partition is being formatted with NTFS. 6 Click Start to initiate the format request. A message warns you that all data on the disk will be erased. Click OK. 7 Click OK when the Format Complete message appears. Click Close to return to the Disk Administrator window. Notes You can cancel the formatting at any time during the process. However, clicking Cancel will not necessarily restore a volume to its previous state. Before files and directories can be stored on the partitions that you have created, you must first commit the changes to disk, and then individually format each partition with a file system. istrator, are you "commiting changes now" after trying to establish mirror ? maybe try a reboot and see if it will mirror.