Comments on: Why Microsoft is just not ready for the enterprise.

By: Paul

Paul — Wed, 29 Jul 2009 14:18:40 +0000

That’s it exactly. No worries if you don’t know; I was just curious.

By: admin

admin — Wed, 29 Jul 2009 14:07:07 +0000

I understand now. This is more of an approach on which userland applications invoke the API to insure that all operations were successful. Unfortunately, I cannot give you an answer unless a more thorough investigation is conducted.

By: Paul

Paul — Wed, 29 Jul 2009 13:54:12 +0000

Based on the design doc you provided (thanks!) it does seem like it has low-level support for rolling back changes to multiple files at once, but it seems to be focused on filesystem consistancy in the event of crashes - a subtly different use case. Applications must be specially written to take advantage of transactional NTFS. As an example of what it is used for, Windows Installer uses it to ensure that an application is fully installed, or not at all (including registry operations as they are also transacted). Here is the API to open/create a file in transacted mode: http://msdn.microsoft.com/en-us/library/aa363859(VS.85,loband).aspx

So yeah, while copy-on-write systems make roll-backs easy, that’s only a piece of the puzzle. Does Reiser4/Linux support all the necessary pieces?

By: admin

admin — Wed, 29 Jul 2009 13:32:31 +0000

Paul,

Here is the Reiser4 design documentation. It supports atomic transaction as in "all or nothing." But note that this will always be the case with a file system that utilizes a Copy-On-Write mechanism for write operations. It will always have something to fall back to if a failure occurs.

By: Paul

Paul — Wed, 29 Jul 2009 13:17:42 +0000

>>Oh yeah, it also supports atomic transactions. Are there any other mainstream
>>file systems that support this feature?

>The first ones that come up to mind are ZFS, XFS, NetApp’s WAFL, Reiser4 and I am sure there are more.

I don’t mean single-file transaction support (as in journaling), I mean where you can encapsulate changes to multiple files and then commit all the changes or roll them back as a single unit (i.e. if any single file operation fails, everything is rolled back). See http://en.wikipedia.org/wiki/Transactional_NTFS for more info.

If that is what you meant; if so, have you got a link?

By: admin

admin — Wed, 29 Jul 2009 12:44:11 +0000

Paul,

Thank you very much for the feedback. It is very much appreciated. Note that I have never touched Windows Vista and only briefly played with Server 2008. I was unaware that online volume resizing was implemented within these releases. Again thank you for the your comments.

With regards to your question:

>>Oh yeah, it also supports atomic transactions. Are there any other mainstream
>>file systems that support this feature?

The first ones that come up to mind are ZFS, XFS, NetApp’s WAFL, Reiser4 and I am sure there are more.

By: Paul

Paul — Wed, 29 Jul 2009 12:27:37 +0000

Oh yeah, it also supports atomic transactions. Are there any other mainstream file systems that support this feature?

By: Paul

Paul — Wed, 29 Jul 2009 12:23:49 +0000

NTFS doesn’t support tail-packing but it does support packing the file data in with the metadata - if the file is small enough. So call that partial support.

The built-in tools in Windows Vista/Server 2008 allow live volume resizing.

Windows isn’t limited to 23 volumes - mount points have been supported since Windows 2000 (where you mount a drive as a folder). If you have more than 23 volumes then you are unlikely to find this complicated (it’s available in the GUI management tool).

Also, if you want to list the flaws of NTFS, why don’t you list the good bits too? Like the fact that it supports a wide range of features, including transparent encryption and compression, snapshots, sparse files and quotas. Or the fact that it is extremely mature and well trusted technology (unlike BTRFS and even ZFS) which is especially important in the enterprise.