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Server 2008 disk mirror - "no extents were found for the plex" RRS feed

  • Question

  • Help! I'm trying to setup a disk mirror on a Windows 2008 server (web edition). The server contains 2 identical 18Gb SCSI disks, both of which are working as far as I can see - I can create volumes, put data on, move data around etc with no problems whatsoever.

    I removed all the volumes from the second disk and made sure both disks are set to dynamic. When I right click on the volume on the first disk, the option to 'Add Mirror' is available (ie not greyed out), but when I click on it a window pops up saying "no extents were found for the plex".

    I've searched high and low - nowhere can I find any reference to this problem at all! If anyone can even tell me what this message means I'd be grateful.
    Thanks.
    Friday, October 17, 2008 2:04 PM

Answers

  • I don't make software mirrors that often and couldn't test but if memory serves I believe the second disk should not be set to dynamic.  Only the source disk should be dynamic.  The other should basically just be there.  Not allocated, I'm not certain if initialized matters.
    http://www.chrislooney.com MCITP: Enterprise Administrator (Server 2008), MCSE: Security 2003/2000, MCSE: Messaging 2003/2000, MCITP: Exchange 2007, MCTS:SharePoint 2007 (Admin, and Develop), MCTS: SQL 2005, MCDBA, MCAD, MCDST, MCSA, CCNA, CCSP, Security+, OCDBA
    • Proposed as answer by Chris Looney Tuesday, October 21, 2008 3:11 PM
    • Marked as answer by David Shen Wednesday, October 22, 2008 1:47 AM
    Friday, October 17, 2008 4:23 PM

All replies

  • I don't make software mirrors that often and couldn't test but if memory serves I believe the second disk should not be set to dynamic.  Only the source disk should be dynamic.  The other should basically just be there.  Not allocated, I'm not certain if initialized matters.
    http://www.chrislooney.com MCITP: Enterprise Administrator (Server 2008), MCSE: Security 2003/2000, MCSE: Messaging 2003/2000, MCITP: Exchange 2007, MCTS:SharePoint 2007 (Admin, and Develop), MCTS: SQL 2005, MCDBA, MCAD, MCDST, MCSA, CCNA, CCSP, Security+, OCDBA
    • Proposed as answer by Chris Looney Tuesday, October 21, 2008 3:11 PM
    • Marked as answer by David Shen Wednesday, October 22, 2008 1:47 AM
    Friday, October 17, 2008 4:23 PM
  • I have the same error. No idea what does it mean...
    Sunday, December 21, 2008 5:46 AM
  • Both discs need to unallocated the mirror pop up will set them both to Dynamic when it formats them.
    Friday, January 30, 2009 10:06 PM
  • Dugster said:

    Both discs need to unallocated the mirror pop up will set them both to Dynamic when it formats them.

    Only the one being added needs to be empty.

    It needs to have atleast as much empty space as the disk being mirrored.

    An alternative to Disk Management is the diskpart.exe command line utility.  See:
    http://technet.microsoft.com/en-us/library/cc766465.aspx.

    From what I recall from the last time I did it, the disk being added needs to already be dynamic.

    One problem can be if the two disks were previously used dynamically together in Windows.  Windows puts a database on each disk containing the dynamic disk data.  To avoid this problem, use the clean command in diskpart to clean the disk being added.  Then you can convert it to dynamic and add it to mirror the disk with the data.  You might need to rescan before you convert.
    • Proposed as answer by David Shen Tuesday, February 3, 2009 1:41 AM
    Monday, February 2, 2009 9:15 PM
  • I also encountered this error.

    I had the OS (C:) volume, a DATAPART1 (D:) volume, and a RECOVERY (F:) volume on the first disk. I wanted to mirror all three volumes to the second disk.

    I used the Server Manager > Storage > Disk Management tool.

    In my first attempt at mirroring all three volumes, I right clicked each volume (starting with the DATAPART1 [D:] volume) and used the "Add Mirror..." function. This worked for all volumes except the OS (C:) volume, which is when I received the "no extents were found for the plex" error.

    My solution was to remove all of the mirrors from the second disk (right click > "Remove Mirror..."), and then re-add all of the mirrors as before, EXCEPT this time I mirrored the OS (C:) volume FIRST.

    This time everything worked fine. It seems as though you simply need to mirror the system (C:) volume before any other volume.
    • Proposed as answer by BMoorePSU Wednesday, March 16, 2011 10:16 PM
    Tuesday, June 30, 2009 6:59 PM
  • It would seem that when you mirror the "boot" volume (%SystemDrive%), it has to be active and the first volume on the mirror disk.

    This probably has to do with bootable dynamic volumes needing an underlying partition table entry.

    When setting up a dynamic drive with diskpart.exe, you can use the RETAIN command to ensure this.
    Tuesday, June 30, 2009 7:25 PM
  • Yep, that did it for me...same issue and just mirror the sys vol 1st. [Well, not exactly the same issue.  I wanted to mirror a Win7 install.  Win7 creates a small "reserved" partition in addition to the main 'C.'  Apparently this vol must be 'mirrored' 1st.]

    PS  The 2nd disk must be unpartitioned and set as 'Dynamic' -- old server 2003 would just error-out.  Now server 2008 prompts and then converts for you (smarter) before doing the mirror.
    • Proposed as answer by Brian Borg Friday, July 10, 2009 12:27 AM
    Thursday, July 9, 2009 5:49 PM
  • RkHosey, you are correct.

    I had forgotten about that 200 MB "hidden" partition.

    Disk Manager will show this as the System volume (not to be confused with the %SystemDrive%, which is the Boot volume).

    Note, you are allowed to "unhide" that partition by assigning it a drive letter or mount point.

    It is also interesting to note that once assigned a letter, Disk Manager will not let you remove the assignment.  But you can remove the assignment using DiskPart.  Go figure.
    Friday, July 10, 2009 12:35 AM
  • Don't forget to add the drive must finish its resync before you can add addition mirrors for other partitions.
    Rich Stuckey
    Wednesday, July 29, 2009 4:15 PM
  • Diskpart solved this for me.

    Ran cmd prompt diskpart

    cleaned target drive.

    be sure to clean correct disk !

    softmirror worked straight away.

    Monday, October 18, 2010 7:39 AM
  • That did it for me.  I had a drive fail, and I was using Windows raid because I didn't want to be dependent on proprietary raid hardware.

    It was in a RAID 1 configuration, and one drive failed.  I replaced the drive and got the error about extents not being found.

    I noticed that the drive I wanted to use had a small partition of about 110MB that I could not erase.

    In server 2008 r2, I opened a command prompt as administrator, typed diskpart.

    The new drive that I wasn't able to allocate was disk 1, so I typed 'select disk 1', hit enter, then typed 'clean'.

    The small partition disappeared, and I was able to complete the Add Mirror operation on disk 0, with disk 1 as the destination.

    Thank you,

    --Evan


    Evan Soenke
    Tuesday, September 27, 2011 7:57 PM
  • Mark, this simple solution did the trick when I had the same problem, thanks for the help

    -from the future

    Tuesday, June 26, 2012 6:08 PM
  • What i Did was to remove the mirror from Disk 0 and add mirror to the "system Partition" in disk 0 first, then added the C: partition and added mirror to that using the same disk 1. This time the error for "No extents were found for the plex" is no longer present. resolved for me.
    Monday, November 30, 2015 5:32 PM