FILE_WRITE_THROUGH question

NTFSD
1

Hi all,

Can anyone explain to me exactly how the FO_WRITE_THROUGH file object flag
affects the cache manager? Does the cache manager know to write through by
looking at this flag when the cache map is initialized, or during
CcCopyWrite? I tried looking through FastFat to check the behavior of a
file system when the FILE_WRITE_THROUGH create option is set, but fastfat
seems to not even check for this flag in the create path! Am I missing
anything?

Thanks,
Matt

2

Right, this is done inside the cache manager - it writes to cache and
then flushes the cache behind the write operation. That’s why FAT
doesn’t even look at it.

Regards,

Tony

Tony Mason
Consulting Partner
OSR Open Systems Resources, Inc.
http://www.osr.com

-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of Matthew N. White
Sent: Friday, July 08, 2005 1:19 PM
To: ntfsd redirect
Subject: [ntfsd] FILE_WRITE_THROUGH question

Hi all,

Can anyone explain to me exactly how the FO_WRITE_THROUGH file object
flag
affects the cache manager? Does the cache manager know to write through
by
looking at this flag when the cache map is initialized, or during
CcCopyWrite? I tried looking through FastFat to check the behavior of a
file system when the FILE_WRITE_THROUGH create option is set, but
fastfat
seems to not even check for this flag in the create path! Am I missing
anything?

Thanks,
Matt

Questions? First check the IFS FAQ at
https://www.osronline.com/article.cfm?id=17

You are currently subscribed to ntfsd as: xxxxx@osr.com
To unsubscribe send a blank email to xxxxx@lists.osr.com

3

It affects the FSD and not the cache manager, and causes any cached writes
to be immediately flushed by CcFlushCache.

Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
xxxxx@storagecraft.com
http://www.storagecraft.com

----- Original Message -----
From: “Matthew N. White”
To: “Windows File Systems Devs Interest List”
Sent: Friday, July 08, 2005 9:18 PM
Subject: [ntfsd] FILE_WRITE_THROUGH question

> Hi all,
>
> Can anyone explain to me exactly how the FO_WRITE_THROUGH file object flag
> affects the cache manager? Does the cache manager know to write through by
> looking at this flag when the cache map is initialized, or during
> CcCopyWrite? I tried looking through FastFat to check the behavior of a
> file system when the FILE_WRITE_THROUGH create option is set, but fastfat
> seems to not even check for this flag in the create path! Am I missing
> anything?
>
> Thanks,
> Matt
>
>
>
> —
> Questions? First check the IFS FAQ at
https://www.osronline.com/article.cfm?id=17
>
> You are currently subscribed to ntfsd as: xxxxx@storagecraft.com
> To unsubscribe send a blank email to xxxxx@lists.osr.com