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Cannot Complete Synchronization RRS feed

  • Question

  • This is my first experiencing using a Windows Home server product and the install and configuration went smoothly. I installed 2 2TB drives for storage and remove the system drive from the storage pool. The Server Storage showed 3310 GB of total space. With folder duplication turned on, I figured I had about half of that, or 1655 GB of actual storage space. I then started copying my music and video files over which totals 1800.4 GB (138.9 GB of music and 1661.5 GB of video). I copied them over in chunks to make sure I didn't run out of space in the middle of transferring a big chunk of files. As I got close to being full, I eventually received a critical alert: 

    Cannot complete synchronization

    There is not enough drive space on Server Storage to complete synchronization for the following folder(s):
    Videos
    Some of the folders may not be fully duplicated or, hard drive removals maybe paused.

    Resolve this alert

    To resolve this issue, add additional hard drives to Server Storage.

     

    The error message details how to fix the issue, which involves adding another hard drive, which I did. Assuming the issue would resolve itself and the drives would balance out the data, I began copying the rest of my files over. What happened instead is something I still can't figure out. The files will copy over just fine because the physical disk space is there, but I continue to receive this alert that there are files on the drive that can't be synchronized and I need to add another drive to correct the problem.

    Is there something different I need to do? I'm already up to what should be approximately 4965 GB of storage (as reported in Dashboard) for 1800 GB of data. Even with duplication turned on, the Dashboard reports I should have 1285 GB of free space. It just doesn't seem like Vail is correctly balancing the system and moving files from drive to drive so they'll duplicate correctly and the alert will go away. Throwing another 2TB drive in the system isn't making the best sense and will run me another $110-$140.

    Tuesday, July 6, 2010 5:43 PM

Answers

  • An example: You have two 2 TB drives. You turn duplication on for all shares, backups, etc. You then begin copying data to your server. You keep doing so until you've copied about 1.55 TB of data, at which point you get the warning you've already seen. Your two initial drives are full; there's no more room for duplication on them. You add one drive and start copying again. There's still no room for duplication, because two of your three drives are already full. This is where you are today.

    Now, certainly Drive Extender could try to use an intelligent algorithm to move files around and do some sort of "load balancing". But if it did so, it would be doing so constantly, because it's unlikely that anyone's storage could ever be perfectly balanced. Every time you add, change, or delete a file, your server would start churning away. Also, there's a performance consideration. In your case shifting data to fill the new drive up to 50% utilization would require moving ~650 GB of data off of one of your drives and onto the new 1.5 TB drive, which would leave you with two drives each having about 650 GB of free space. Moving 650 GB would probably take at least a few hours, during which server performance would probably be noticeably impacted.

    tl;dr version: if you're using duplication (and you should) throw drives at your server in pairs.


    I'm not on the WHS team, I just post a lot. :)
    Tuesday, July 6, 2010 7:44 PM
    Moderator

All replies

  • An example: You have two 2 TB drives. You turn duplication on for all shares, backups, etc. You then begin copying data to your server. You keep doing so until you've copied about 1.55 TB of data, at which point you get the warning you've already seen. Your two initial drives are full; there's no more room for duplication on them. You add one drive and start copying again. There's still no room for duplication, because two of your three drives are already full. This is where you are today.

    Now, certainly Drive Extender could try to use an intelligent algorithm to move files around and do some sort of "load balancing". But if it did so, it would be doing so constantly, because it's unlikely that anyone's storage could ever be perfectly balanced. Every time you add, change, or delete a file, your server would start churning away. Also, there's a performance consideration. In your case shifting data to fill the new drive up to 50% utilization would require moving ~650 GB of data off of one of your drives and onto the new 1.5 TB drive, which would leave you with two drives each having about 650 GB of free space. Moving 650 GB would probably take at least a few hours, during which server performance would probably be noticeably impacted.

    tl;dr version: if you're using duplication (and you should) throw drives at your server in pairs.


    I'm not on the WHS team, I just post a lot. :)
    Tuesday, July 6, 2010 7:44 PM
    Moderator
  • Something to try, it worked for me on V1.  Turn duplication off and wait until the duplicates are deleted.  Now turn duplication back on and the duplicates will be distributed more equally, not perfectly, but better than your current situation. 
     
    Keep in mind that turning duplication off may put your data at risk until you turn it back on again and it is fully replicated.

    --

    BulllDawg
    In God We Trust
     

    This is my first experiencing using a Windows Home server product and the install and configuration went smoothly. I installed 2 2TB drives for storage and remove the system drive from the storage pool. The Server Storage showed 3310 GB of total space. With folder duplication turned on, I figured I had about half of that, or 1655 GB of actual storage space. I then started copying my music and video files over which totals 1800.4 GB (138.9 GB of music and 1661.5 GB of video). I copied them over in chunks to make sure I didn't run out of space in the middle of transferring a big chunk of files. As I got close to being full, I eventually received a critical alert: 

    Cannot complete synchronization

    There is not enough drive space on Server Storage to complete synchronization for the following folder(s):
    Videos
    Some of the folders may not be fully duplicated or, hard drive removals maybe paused.

    Resolve this alert

    To resolve this issue, add additional hard drives to Server Storage.

     

    The error message details how to fix the issue, which involves adding another hard drive, which I did. Assuming the issue would resolve itself and the drives would balance out the data, I began copying the rest of my files over. What happened instead is something I still can't figure out. The files will copy over just fine because the physical disk space is there, but I continue to receive this alert that there are files on the drive that can't be synchronized and I need to add another drive to correct the problem.

    Is there something different I need to do? I'm already up to what should be approximately 4965 GB of storage (as reported in Dashboard) for 1800 GB of data. Even with duplication turned on, the Dashboard reports I should have 1285 GB of free space. It just doesn't seem like Vail is correctly balancing the system and moving files from drive to drive so they'll duplicate correctly and the alert will go away. Throwing another 2TB drive in the system isn't making the best sense and will run me another $110-$140.


    BullDawg
    Tuesday, July 6, 2010 9:32 PM
  • Excuse me for sounding ignorant, I'm still learning about WHS, but isn't it supposed to use some kind of load balancing to redistribute the files? If the point of Drive Extender is to allow me to add storage as I need it, it makes sense to me it should redistribute the files so there is an equal share on each drive to allow them to fill back up. If this, however, isn't how Driver Extender is supposed to work, then it does seem to make sense to add a pair of drives so the new files have a place to be duplicated.

    Since I still have a backup of all my files on another system and on an external HDD, as a test, I'll turn duplication off, wait for it to delete the duplicates, then turn it back on. It will be good to know how all of this works while the server is still young to avoid any future headache/heartache. I'll report back what happens.

    Wednesday, July 7, 2010 4:21 AM
  • At present, no "load balancing" is done. Files are moved around from disk to disk only when a disk is removed from server storage. Other than that, Drive Extender attempts to "balance" where new files are created, but leaves them alone otherwise.
    I'm not on the WHS team, I just post a lot. :)
    Wednesday, July 7, 2010 9:49 AM
    Moderator
  • Drive Balancer is ineffective on Vail, because it works with disks, and Vail doesn't expose disks to programs, only the "virtual" disks that contain the shares.
    I'm not on the WHS team, I just post a lot. :)
    Wednesday, July 7, 2010 12:31 PM
    Moderator
  • I tried what BullDawg suggested and turned off duplication on all my shares, allowed the duplicates to delete, and then turned it back on one share at a time and waited for it to synchronize. I'm happy to report that seemed to work. My numbers are below.

    With duplication turned off:

    Free space: 3098
    Total space: 4965

    WD 2TB 1 1863 GB
        383.6 GB free

    WD 2TB 2 1863 GB
        1239.8 GB free

    WD 2TB 3 1863 GB
        1861.9 GB free

    After turning duplication back on:

    Free space: 1240 GB
    Space used for dup: 1858 GB

    WD 2TB 1 1863 GB
        383.6 GB free

    WD 2TB 2 1863 GB
        515.2 GB free

    WD 2TB 3 1863 GB
        496.1 GB free

    After turning duplication back on and waiting for it to finish synchronizing (which took 10 hours!) it seems things balanced out pretty well. Because of the time, and potential loss of data, involved with doing it this way, I may just have to add drives in pairs, as Ken suggests.

    Thursday, July 8, 2010 12:22 AM