From mboxrd@z Thu Jan 1 00:00:00 1970 From: "H. Peter Anvin" Subject: Re: [ANNOUNCE] util-linux-ng v2.17 (stable) Date: Fri, 08 Jan 2010 15:33:17 -0800 Message-ID: <4B47C0BD.5010700@zytor.com> References: <20100108093302.GS1969@nb.net.home> <4B47A713.9060405@zytor.com> <329167C1-CF54-4742-B0B7-AD0B9DEFDEC1@sun.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Karel Zak , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, util-linux-ng-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Andreas Dilger Return-path: In-Reply-To: <329167C1-CF54-4742-B0B7-AD0B9DEFDEC1-xsfywfwIY+M@public.gmane.org> Sender: util-linux-ng-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-fsdevel.vger.kernel.org On 01/08/2010 02:40 PM, Andreas Dilger wrote: > On 2010-01-08, at 14:43, H. Peter Anvin wrote: >> On 01/08/2010 01:33 AM, Karel Zak wrote: >>> fdisk: >>> - the fdisk command aligns newly created partitions to >>> minimum_io_size >>> boundary ("minimum_io_size" is physical sector size or stripe >>> chunk >>> size on RAIDs). >>> >>> - the fdisk command supports disks with alignment_offset now. >> >> I think we should align, by default, much more aggressively than >> that -- >> because frequently we just don't know what the real physical alignment >> is (think of flash media, which uses large erase blocks underneath.) >> Windows aligns partitions 1 MB boundaries by default now -- I think >> that's probably a reasonably good idea, at least for any disk that's >> not >> tiny, say 256 MB or less. > > I agree whole heartedly. We steer users very sharply away from using > partitions at all, because on h/w RAID devices the 512-byte offset > from fdisk completely kills RAID-5/6 performance. > > Making the default minimum alignment for DOS/GPT partitions makes a > lot of sense, and LVM PEs should be on 1MB boundaries as well (I don't > think that is the case today either). > As far as I can tell, there is absolutely no reason to not align all partitions, all the time (for both GPT and MBR... GPT may need a "dummy alignment partition" to fulfill the "no nonpartitioned space" dictum, although it seems like an impossible requirement in practice -- I think they main reason for it is to avoid abusers like Grub relying on putting data in unpartitioned space.) -hpa -- To unsubscribe from this list: send the line "unsubscribe util-linux-ng" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html