$MFT zone reservation; glitches?

[DiracDeBroglie]

I fully agree with your critical view, jaclaz. Still working on another problem now. I'll be back.

Johan

[jaclaz]

Still working on another problem now. I'll be back.

No prob whatsoever.

Corollary to my previous post is that since the two different ways to set the NtfsMftZoneReservation were respectively set with Win NT 4.0 Service Pack 4 (SP4) and changed with Vista

http://technet.microsoft.com/en-us/library/cc767961.aspx

http://support.microsoft.com/default.aspx?scid=kb;en-us;174619&sd=tech

http://support.microsoft.com/?id=961095

and this issue was never AFAIK/AFAICR raised, I would rate the priority of the theoretical problem as extremely low.

Seemingly - and at least initially - the setting was "carved in stone" and only applied to newly created filesystems:

http://technet.microsoft.com/en-us/library/cc767961.aspx

You must change this Registry setting prior to the creation of an NTFS volume. The modification affects only those volumes created after you create this Registry entry—the modification doesn't change existing NTFS volumes, which retain their original MFT zone reservations. Also, allocating more space for the MFT won't limit the amount of free disk space available for regular file storage, because NTFS will use the MFT zone if the normal user file area becomes full.

jaclaz

Edited February 25, 2012 by jaclaz

[DiracDeBroglie]

I don't expect any *big* or *serious* problems with an MFT zone reservation that flips forth and back from large (GBs) to small (MBs) when one switches between WinXP and Win7 machines, especially when the drive is meant for data storage and not as a boot drive; MicroSoft would've detected it years ago if it were otherwise.

But anyhow, you never know that this issue may have some nasty unexpected side effects somehow. Just image, you got a dual boot system with WinXP first installed followed by a Win7 installation on another partition. After booting from Win7, Win7 can see the WinXP partition and shrinks the MFT zone to just over 200MB, from an initial size of GBs. If under a Win7 boot one then drops a file onto the WinXP partition, it may very well be that this userdata file comes right behind the 200MB MFT zone on the WinXP partition, blocking any possible expansion of the MFT zone if one boots next time into WinXP. If the user at a later time installs more apps onto the WinXP partition, no doubt that it will be more likely that the MFT will become fragmented and scattered all of the partition, leading to some WinXP performance degradation.

Also for RAIDs and NAS servers, which I have no experience with, I got a question. Imagine a home network with WinXP and Win7 machines all communicating with a RAID or NAS configuration for data storage. Are RAID and NAS servers transparent enough to let the WinXP and Win7 machines change the MFT zone reservations on the drives in the servers? If yes, one second a WinXP machine creates a large MFT zone when accessing the server, a fraction of a second later the MFT zone gets shrunk to just 200MB when an Win7 machine gets access. A process like that could flip-flop the MFT zone forth and back in size many times per minute until there is enough data on the drive to encapsulated the smallest MFT zone reservation (200MB). I'm not sure if this could happen, it is just that in a year or 2 I may consider purchasing a RAID or NAS configuration.

BTW. I just tried *fsutil behavior set mftzone <n>* in an elevated cmd promp in Win7. It works, but I got a message saying the new setting requires a reboot to take effect. In WinXP the command works as well but does not give a notification to reboot, although a reboot is required in WinXP too. Note that in WinXP the fsutil command does not appear in the command list after typing help in the prompt. It really makes me wonder about the usefulness and the effectiveness of the possibility to change the MFT Zone Reservation, especially with servers that never reboot (as mentioned earlier by jaclaz).

Johan