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4096 bytes sectors..

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Hi, as you know, manufacturers are moving to a new internal hard drive format, (Western Digital mostly) were sectors are 4096 bytes size, discarding the old one of 512 bytes.


As I have understood only systems "legacy" as Win XP and lower are affected ... you know someone about it, which takes effect systems OS X. .. and the hacks?


I personally think that the old installations based on MBR will suffer performance penalty, and GID based real macswon't have any problem...but...What about bootloaders?


Can i use any new disk with 4096 bytes sector size without care in partition aligment in the bootloader or any other problem? Any real world experience about?


Thanks in advance.

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I wrote an article about this with respect to Linux on IBM developerWorks. You can read that if you like, but keep in mind that it's rather Linux-centric. In theory, the same issues apply to Hackintosh installations, but in practice you're likely to use different partitioning tools. I also don't know how susceptible HFS+ is to the performance problems that Advanced Format disks can provoke.


If you use Apple's Disk Utility to partition the disk from the start, you shouldn't have problems, since Disk Utility aligns all partitions to 4096-byte boundaries by default.


If you initially set the disk up using a utility in another OS, then it depends on the OS and utility, but in general, all bets are off. If you used the default Windows Vista or Windows 7 utility, you should be OK; but if you used most others, the chances of your having problems are rather high.


If you're in doubt, I recommend you check it out with a utility that provides sufficient precision about the location of each partition's first sector (many disk utilities are lacking in this regard). I'm most familiar with Linux tools, so I'll suggest you get the System Rescue CD or PartedMagic (two Linux-based emergency recovery systems), boot it, open a text-mode prompt, and type "fdisk -lu /dev/sda" (for MBR disks) or "gdisk -l /dev/sda" (for GPT disks) to view your disk. (You may need to change the device ID from /dev/sda to /dev/sdb, /dev/sdc, /dev/hda, or something else. Type "ls /dev/[hs]d?" to see your available disk devices.) The results will look something like this (shown for both MBR and GPT disks on one of my Linux systems):


# gdisk -l /dev/sda
GPT fdisk (gdisk) version 0.6.8

Partition table scan:
 MBR: protective
 BSD: not present
 APM: not present
 GPT: present

Found valid GPT with protective MBR; using GPT.
Disk /dev/sda: 1953525168 sectors, 931.5 GiB
Logical sector size: 512 bytes
Disk identifier (GUID): 2E8FE240-FC7A-0294-7068-8EB94CBF4005
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 1953525134
Partitions will be aligned on 8-sector boundaries
Total free space is 6 sectors (3.0 KiB)

Number  Start (sector)	End (sector)  Size	   Code  Name
  1			  40			 439   200.0 KiB   EF02  BIOS boot partition
  2			 440		  410039   200.0 MiB   EF00  EFI System
  3		  410040		  819639   200.0 MiB   0700  Linux /boot (unused)
  4		  819640		 1229239   200.0 MiB   0700  Linux /boot (unused)
  5		 1229240	  1953525134   930.9 GiB   8E00  Linux LVM

# fdisk -lu /dev/sdb

Disk /dev/sdb: 320.1 GB, 320072933376 bytes
255 heads, 63 sectors/track, 38913 cylinders, total 625142448 sectors
Units = sectors of 1 * 512 = 512 bytes
Disk identifier: 0x00022117

  Device Boot	  Start		 End	  Blocks   Id  System
/dev/sdb1   *		  63	  192779	   96358+  83  Linux
/dev/sdb2		 1012095   625137344   312062625   8e  Linux LVM
/dev/sdb3		  192780	 1012094	  409657+  82  Linux swap / Solaris

Partition table entries are not in disk order


Note the "Start" column in both types of output. If the values are multiples of 8, you're fine. If not, then you'll have problems. In this example, the first disk is properly aligned, but the second one isn't. (The second disk in my example isn't actually an Advanced Format disk, so it doesn't actually have any problems. It was just handy as an example.)


You can use the techniques described in the article to which I linked earlier to create new partitions for a Hackintosh install, or use Disk Utility if that's practical. If you've got a disk that's already suboptimally configured, perhaps you can use the utility provided by Western Digital on their Web site to fix the disk.

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Superb reply, totally speechless.

Thank you very much, now i understand it perfectly (almost)

Talking about partitions tools i will give a try PartedMagic, but wanna try with WinHex (win32 hdd forensic tool, very cool)

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