On Mon, Dec 13, 2010 at 05:40:42PM -0600, Stan Hoeppner wrote: > Jochen Schulz put forth on 12/13/2010 3:51 PM: > > Mike Viau: > >>> On Mon, 13 Dec 2010 21:46:59 +0100 <m...@well-adjusted.de> wrote: > >>> > >>> Partition 1 does not start on physical sector boundary. > >> > >> I don't understand the implied meaning of this error? Did you take any > >> precautions as to the alignment of your partition? What about if you > >> were planning on having multiple partitions? > > >From the linux-ide mailing list April 2010: > > http://www.spinics.net/lists/linux-ide/msg37306.html > > Unfortunately, sfdisk and cfdisk have no clue about alignment and > disks topology. > > Now only the fdisk and parted commands are ready for new disks. > > > So the proper title of this thread should be: > > "Does the Squeeze installer use fdisk or parted?" > > As of April 2010, only fdisk and parted will create sector boundary > aligned partitions on drives that internally translate from 4K to 512B > sectors. > > Linux typically reads 4K blocks. With a translated drive, two or more > 512 byte sectors of a given block may lie on opposite sides of a > hardware 4K sector boundary. Thus, Linux will have to read two > consecutive hardware sectors instead of one in order to get the contents > of the 4K logical block. I.e. two reads (head seeks) per every 4k block > instead of one. Thus, you get half the performance vs a properly > aligned cylinder. > > In the case of the WD20EARS this will drop your peak sequential read > rate from over 100 MB/s down to 50 MB/s or less. Without proper > alignment, you're literally leaving half of your drive's sequential read > performance on the table. > > The story is even worse for 4K random writes. You'll drop your write > performance by a factor of 4 or more if you don't have proper alignment: > > The moral of the story is, use fdisk or parted and make sure your > partitions are correctly aligned on 4KB boundaries. If the Squeeze > installer doesn't do so, I'd recommend booting an ISO or USB live distro > and partition the drive with fdisk or parted before booting the Squeeze > installer.
Hi Stan, That is fascinating to learn, especially the fdisk is among the best tools for disk partitioning. I was going to ask about my disk, but I see that my message is Partition 1 does not end on cylinder boundary. Which seems to be different than the OP's physical sector size message. If partition 1 is off, does that mean *all* partitions are off? How does one verify? (I used MiniTool Partition Wizard to shrink my laptop's Windows 7 partition, handling all the magical, Linux-hating files -- MFT, etc.) http://www.partitionwizard.com/free-partition-manager.html FWIW, my disk partitioning follows. Thanks for posting this information! Joel Disk /dev/sda: 320.1 GB, 320072933376 bytes 255 heads, 63 sectors/track, 38913 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x27b11b56 Device Boot Start End Blocks Id System /dev/sda1 * 1 154 1228800 7 HPFS/NTFS Partition 1 does not end on cylinder boundary. /dev/sda2 154 4742 36860288+ 7 HPFS/NTFS /dev/sda3 4743 5251 4088500 82 Linux swap / Solaris /dev/sda4 5252 38914 270398047+ f W95 Ext'd (LBA) /dev/sda5 5252 7163 15358108 83 Linux /dev/sda6 7164 37638 244790404 83 Linux /dev/sda7 37639 38914 10240000 7 HPFS/NTFS > -- > Stan > > > -- > To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org > with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org > Archive: http://lists.debian.org/4d06aefa.6070...@hardwarefreak.com > -- Joel Roth -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/20101214040331.gb7...@sprite