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  • When WHS auto backup your data it should be able to tell if you have enough space on the WHS hard drive to back up your system.

    For example.

    You have a WHS server with a 250GB Hard Drive. You also have 3 computers you would like to back up that their Hard drive space, for all three of them, is 750GB. Now ofcourse you can not back up all 750GB of space.

    So WHS should just give a warning to the user that they can not back up all 750GB of space and they should choose what they would like to back up from each computer so that it may fit on the 250GB Hard drive WHS has.

    Kind of like when you burn a CD or a DVD, if you went over your space, the program tells you.

    Better yet, i think, (and this is my opinion) the backup process should only include system critical files, instead of all of the hard drives that are present in your computer, and let the user pick what he would like to back up.

     

    Tuesday, March 6, 2007 3:12 AM

Answers

  • Most of that is covered in the release documentation. WHS uses a technology called Single Instance Storage to reduce the size of backups. Here's how it works:

    Backups are stored in a bunch of large files in the file system (call them the repository). Each cluster in those large files is indexed in a database of some sort, and a unique hash value is calculated for it. Now, when you back up a file, each cluster is examined and hashed, and the database is checked for that hash value. If it's found, a cluster with that data is already stored in the backup repository. So when backing up that file, instead of storing the cluster again, a pointer of some sort to the real cluster is stored. (I would guess that that's all that's actually stored for a file, a list of cluster locations.) Anyway, a home with multiple PCs and WHS will probably have a lot of duplication: similar or identical OS files, applications (Microsoft Office, for example), maybe media or documents.

    So instead of it taking as much storage to back up three PCs as there is physically installed in them, it takes up a great deal less. For example, I have three PCs being backed up. Between them, they contain about 400 GB of data, programs, files, etc. My backups (2 weeks worth) take up less than 300 GB of disk space on WHS.

    All that said, there is a disk space limitation in WHS beta 2. If you have, for example, a 40 GB primary disk (the one your system partition and D: partition are on), that disk will have a bit less than 30 GB of free space. Obviously, you can't copy more than 30 GB to WHS in this case. If you then add a 750 GB drive to WHS, you still can't copy more than 30 GB to WHS at a time. So a small primary disk can result in backups failing due to lack of disk space, just because there's more data to back up off a single drive than there is space on the data partition of the primary WHS disk. This limitation is supposed to be removed in the shipping product.

    Do you follow all that?
    Tuesday, March 6, 2007 3:35 AM
    Moderator

All replies

  • Most of that is covered in the release documentation. WHS uses a technology called Single Instance Storage to reduce the size of backups. Here's how it works:

    Backups are stored in a bunch of large files in the file system (call them the repository). Each cluster in those large files is indexed in a database of some sort, and a unique hash value is calculated for it. Now, when you back up a file, each cluster is examined and hashed, and the database is checked for that hash value. If it's found, a cluster with that data is already stored in the backup repository. So when backing up that file, instead of storing the cluster again, a pointer of some sort to the real cluster is stored. (I would guess that that's all that's actually stored for a file, a list of cluster locations.) Anyway, a home with multiple PCs and WHS will probably have a lot of duplication: similar or identical OS files, applications (Microsoft Office, for example), maybe media or documents.

    So instead of it taking as much storage to back up three PCs as there is physically installed in them, it takes up a great deal less. For example, I have three PCs being backed up. Between them, they contain about 400 GB of data, programs, files, etc. My backups (2 weeks worth) take up less than 300 GB of disk space on WHS.

    All that said, there is a disk space limitation in WHS beta 2. If you have, for example, a 40 GB primary disk (the one your system partition and D: partition are on), that disk will have a bit less than 30 GB of free space. Obviously, you can't copy more than 30 GB to WHS in this case. If you then add a 750 GB drive to WHS, you still can't copy more than 30 GB to WHS at a time. So a small primary disk can result in backups failing due to lack of disk space, just because there's more data to back up off a single drive than there is space on the data partition of the primary WHS disk. This limitation is supposed to be removed in the shipping product.

    Do you follow all that?
    Tuesday, March 6, 2007 3:35 AM
    Moderator
  •  F14Mavrick wrote:
    When WHS auto backup your data it should be able to tell if you have enough space on the WHS hard drive to back up your system.

    Not a bad idea... only remember that under WHS with the single instance backups it is possible for that 750 gigs to fit into a much smaller space depending on what it is... it’s kind of like estimating the final size of a compressed file/folder when you only know the size of what’s going in and not the contents of what is going in or how well it’ll compress.

     F14Mavrick wrote:
    Better yet, i think, (and this is my opinion) the backup process should only include system critical files, instead of all of the hard drives that are present in your computer, and let the user pick what he would like to back up.

    The default is to backup everything and once setup, you are free to exclude anything you want including to the point where only your... Documents and Settings (Users under Vista) and Windows directories are backed up.

    Tuesday, March 6, 2007 3:38 AM
    Moderator
  •  Ken Warren wrote:
    Most of that is covered in the release documentation. WHS uses a technology called Single Instance Storage to reduce the size of backups. Here's how it works:

    Backups are stored in a bunch of large files in the file system (call them the repository). Each cluster in those large files is indexed in a database of some sort, and a unique hash value is calculated for it. Now, when you back up a file, each cluster is examined and hashed, and the database is checked for that hash value. If it's found, a cluster with that data is already stored in the backup repository. So when backing up that file, instead of storing the cluster again, a pointer of some sort to the real cluster is stored. (I would guess that that's all that's actually stored for a file, a list of cluster locations.) Anyway, a home with multiple PCs and WHS will probably have a lot of duplication: similar or identical OS files, applications (Microsoft Office, for example), maybe media or documents.

    So instead of it taking as much storage to back up three PCs as there is physically installed in them, it takes up a great deal less. For example, I have three PCs being backed up. Between them, they contain about 400 GB of data, programs, files, etc. My backups (2 weeks worth) take up less than 300 GB of disk space on WHS.

    All that said, there is a disk space limitation in WHS beta 2. If you have, for example, a 40 GB primary disk (the one your system partition and D: partition are on), that disk will have a bit less than 30 GB of free space. Obviously, you can't copy more than 30 GB to WHS in this case. If you then add a 750 GB drive to WHS, you still can't copy more than 30 GB to WHS at a time. So a small primary disk can result in backups failing due to lack of disk space, just because there's more data to back up off a single drive than there is space on the data partition of the primary WHS disk. This limitation is supposed to be removed in the shipping product.

    Do you follow all that?

    yes and thank you

    Wednesday, March 7, 2007 12:21 AM
  • ok, I'm not sure exactly how this works.. but your saying the largest hard drive must be the primary HD (c,d)  if your example above about the 40gb primary drive, even if you have a second drive that is 300gb it will only copy 30gb?  So if you have a 300gb, and a 40gb you should have the 300gb as the primary drive and the 40gb as the second drive correct?


    Tuesday, March 20, 2007 8:45 PM
  •  tarkwolf wrote:
    So if you have a 300gb, and a 40gb you should have the 300gb as the primary drive and the 40gb as the second drive correct?

    For the time being at least yes.

    Friday, March 23, 2007 1:09 AM
    Moderator
  • When my office laptop backs up to the corporate backup site, the % complete keeps on reviewing. It would be frustrating to see 60% complete go back to 39% as I will have to wait more time to shutdown or close the lid.

    However that could be one way of getting to know whether the backup fits into the available space. That is dynamically keep calculating the space required and that's what is happening on WHS.

    But that is not at all good for the resource planning. After all the compression algorithm is based on some math. Then why can't we calculate before hand? This may take more time to backup.

    As such the connector app in the sys tray can keep monitoring the data to be backed up and calculate the space required for backing up and inform before hand about the impending disaster of insufficient space. Why, is it not possible?

    ThanQ...

    Monday, March 26, 2007 7:07 PM