On Fri, 13 Jun 2008, Al Hopper wrote: > storage sub-system. Currently, ZFS determines if the access pattern > is random or sequential and there is no mechanism to provide it with > "hints".
Right. But this untunable generality may prevent it from being used for real-time uncompressed 2K resolution video server use where it does not take many disk seeks to cause stutters. > Yes - this is a lofty and worthy goal and it would appear, upon first > blush, that to provide a "hints" facility would make sense - but Team > ZFS are the ultimate look-to-the-future designers and believe, that if > the current implement is deficient, the next implementation will > simply be better. This philosophy means that the user will never have > to change a single line of code or a learned (keyboard) behavioral > pattern. This POSIX interface simply requests to reserve space in advance from the filesystem. Even if fragmentation is not considered, there is a worthy purpose to this since an error message can be returned more quickly to the user rather than taking minutes or hours. It assures that the task will not fail mid-way due to lack of disk space. Of course when compression is enabled, it is not possible to accurately reserve space. > Given that machines keep getting faster and that more and more CPU > cycles can be dedicated to "letting the machine do the work" - this > philosophy is the correct approach IMHO. But is counter-intuitative Maybe once all rotating disk drives are replaced with solid state devices, then CPU cycles would make a difference but currently we are facing disk seeks which are not getting much faster. Bob ====================================== Bob Friesenhahn [EMAIL PROTECTED], http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/ _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
