On Sep 15, 2010, at 2:18 PM, Edward Ned Harvey wrote: >> From: Richard Elling [mailto:rich...@nexenta.com] >> >>> Suppose you want to ensure at least 99% efficiency of the drive. At >> most 1% >>> time wasted by seeking. >> >> This is practically impossible on a HDD. If you need this, use SSD. > > Lately, Richard, you're saying some of the craziest illogical things I've > ever heard, about fragmentation and/or raid. > > It is absolutely not difficult to avoid fragmentation on a spindle drive, at > the level I described. Just keep plenty of empty space in your drive, and > you won't have a fragmentation problem. (Except as required by COW.) How > on earth do you conclude this is "practically impossible?"
It is practically impossible to keep a drive from seeking. It is also practically impossible to keep from blowing a rev. Cute little piggy, eh? :-) > For example, if you start with an empty drive, and you write a large amount > of data to it, you will have no fragmentation. (At least, no significant > fragmentation; you may get a little bit based on random factors.) As life > goes on, as long as you keep plenty of empty space on the drive, there's > never any reason for anything to become significantly fragmented. > > Again, except for COW. It is known that COW will cause fragmentation if you > write randomly in the middle of a file that is protected by snapshots. IFF the file is larger than recordsize. -- richard _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
