>Hi there,
>
>I've got an interesting question for you : how do you precompact a VHD with
>an Unix filesystem for reducing VHD file size ?
>
>I tried to reproduce the action of precompactor.exe on Unix (replacing
>deleted files' bytes by bytes of zeros), but I did'nt manage for now.
>
>Have you got any clue about how to do compaction task on a vhd containing a
>Unix based filesystem ?
>
>The short story of my case : for some reasons, we choosed to use Virtual
>Server 2005 to manage the virtualization of our servers. One of them is
>dedicated to continous integration. Its size increased rapidly to reach 45GB,
>even if only 14% are really in use (normal situation, no prob at that point).
>And when I looked for a solution to compact the VHD file, I came to the
>conclusion that Microsoft did not provide the appropriate tool for that.
>As far as I searched on the web, no easy/standard solution exists to compact
>a VHD containing an Unix filesystem.
>
>It would be great if you had some ideas on that!
>
>All the best,
>
>Romain V.
>Hop-Cube (http://www.hop-cube.com)
>France

> On Mon, 14 Sep 2009 06:18:01 -0700, Romain V. <Romain
> (email address - cut out)> wrote:
>
> >Hi there,
> >
> >I've got an interesting question for you : how do you precompact a VHD with
> >an Unix filesystem for reducing VHD file size ?
> >
> >I tried to reproduce the action of precompactor.exe on Unix (replacing
> >deleted files' bytes by bytes of zeros), but I did'nt manage for now.
> >
> >Have you got any clue about how to do compaction task on a vhd containing a
> >Unix based filesystem ?
> >
> >The short story of my case : for some reasons, we choosed to use Virtual
> >Server 2005 to manage the virtualization of our servers. One of them is
> >dedicated to continous integration. Its size increased rapidly to reach 45GB,
> >even if only 14% are really in use (normal situation, no prob at that point).
> >And when I looked for a solution to compact the VHD file, I came to the
> >conclusion that Microsoft did not provide the appropriate tool for that.
> >As far as I searched on the web, no easy/standard solution exists to compact
> >a VHD containing an Unix filesystem.
> >
> >It would be great if you had some ideas on that!
> >
> >All the best,
> >
> >Romain V.
> >Hop-Cube (http://www.hop-cube.com)
> >France
>
> Virtual Server has a tool to compact VHDs. The Precompactor.exe is a
> Windows tool for clearing disk space before you compact.
> Theoretically, you don't need to do this step with a *nix OS, since it
> handles files differently.
>
> Have you tried shutting down the VM and compacting it? From the admin
> page, under Virtual Disks-->Inspect, select the disk, then compact.
>
> --
> Cheers,
> Steve Jain, Virtual Machine MVP
> http://vpc.essjae.com/
>

>Virtual Server has a tool to compact VHDs. The Precompactor.exe is a
>Windows tool for clearing disk space before you compact.
>Theoretically, you don't need to do this step with a *nix OS, since it
>handles files differently.

> In message <(email address - cut out)> "Steve Jain
> [MVP]" <(email address - cut out)> was claimed to have wrote:
>
> >Virtual Server has a tool to compact VHDs. The Precompactor.exe is a
> >Windows tool for clearing disk space before you compact.
> >Theoretically, you don't need to do this step with a *nix OS, since it
> >handles files differently.
>
> Why? *nix OSes don't remove data from disk any more then Windows does,
> unless an OS nulls out files as they're deleted, a precompactor is just
> as needed regardless of the US.
>
> You can probably do it with dd, although I'm not really certain of the
> syntax.
>
> Adding TRIM support to hosts would be an interesting approach since
> modern OSes already have the capability to release clusters no longer
> being used, but it will be at least a generation down the line before we
> see anything like this hitting VM vendor's whiteboards.
>

>"Dave Warren" wrote:
>
>> In message <(email address - cut out)> "Steve Jain
>> [MVP]" <(email address - cut out)> was claimed to have wrote:
>>
>> >Virtual Server has a tool to compact VHDs. The Precompactor.exe is a
>> >Windows tool for clearing disk space before you compact.
>> >Theoretically, you don't need to do this step with a *nix OS, since it
>> >handles files differently.
>>
>> Why? *nix OSes don't remove data from disk any more then Windows does,
>> unless an OS nulls out files as they're deleted, a precompactor is just
>> as needed regardless of the US.
>>
>> You can probably do it with dd, although I'm not really certain of the
>> syntax.
>>
>> Adding TRIM support to hosts would be an interesting approach since
>> modern OSes already have the capability to release clusters no longer
>> being used, but it will be at least a generation down the line before we
>> see anything like this hitting VM vendor's whiteboards.
>>
>
>Hi Dave,
>
>Unix ext3 filesystem format seems to write zeros on a file when deleting it
>while Windows just marks the file as free space in its indexation table.
>(Andreas Dilger, said about it: "In order to ensure that ext3 can safely
>resume an unlink after a crash, it actually zeros out the block pointers in
>the inode, whereas ext2 just marks these blocks as unused in the block
>bitmaps and marks the inode as "deleted" and leaves the block pointers
>alone.")
>
>And if I understand well, precompactor.exe only writes zeros, as etx3 do...

> In message <(email address - cut out)> Romain
> V. <(email address - cut out)> was claimed to have wrote:
>
> >"Dave Warren" wrote:
> >
> >> In message <(email address - cut out)> "Steve Jain
> >> [MVP]" <(email address - cut out)> was claimed to have wrote:
> >>
> >> >Virtual Server has a tool to compact VHDs. The Precompactor.exe is a
> >> >Windows tool for clearing disk space before you compact.
> >> >Theoretically, you don't need to do this step with a *nix OS, since it
> >> >handles files differently.
> >>
> >> Why? *nix OSes don't remove data from disk any more then Windows does,
> >> unless an OS nulls out files as they're deleted, a precompactor is just
> >> as needed regardless of the US.
> >>
> >> You can probably do it with dd, although I'm not really certain of the
> >> syntax.
> >>
> >> Adding TRIM support to hosts would be an interesting approach since
> >> modern OSes already have the capability to release clusters no longer
> >> being used, but it will be at least a generation down the line before we
> >> see anything like this hitting VM vendor's whiteboards.
> >>
> >
> >Hi Dave,
> >
> >Unix ext3 filesystem format seems to write zeros on a file when deleting it
> >while Windows just marks the file as free space in its indexation table.
> >(Andreas Dilger, said about it: "In order to ensure that ext3 can safely
> >resume an unlink after a crash, it actually zeros out the block pointers in
> >the inode, whereas ext2 just marks these blocks as unused in the block
> >bitmaps and marks the inode as "deleted" and leaves the block pointers
> >alone.")
> >
> >And if I understand well, precompactor.exe only writes zeros, as etx3 do...
>
> If I'm reading that correctly, this writes zeros to the block pointers
> themselves, but the actual data itself is left intact.
>