[SOLVED] misaligned extended partition by 1024b

kox444 · 04-04-2014, 08:22 AM

So I got this warning in disk utility that the partition is misaligned and it may result in very poor performance. I can't tell whether the drive is performing well or not because it's a new one and it's certainly faster than the 8 year old HDD I used to use. I've just created new partitions and installed operating systems. I've created partitions using gparted on debian wheezy on old HDD. Then I have installed debian on already existing empty partitions created by gparted. I'm not sure, but I think there was no warning at this point, although I don't remember if I checked disk utility. I had to do a reinstall due to graphics issue. I reformatted partitions using utility in debian installation. I think this could cause this. Now I don't know should I leave it or erase all and start all over again. I won't lose any data because it was copied from old HDD , but a little time for sure.
I've tried to remove empty space in gparted by resizing partition but it resulted in an error. Is there a way to fix this without formatting?
HDD is Seagate Barracuda 1TB.
Partitions:
http://s8.postimg.org/lz9yho4kj/Scre...4_15_17_25.png
90GB free space is left for future installations

smallpond · 04-04-2014, 10:05 AM

If it's an advanced format drive (4K sectors), then you should make sure the partition table has 4K alignment, otherwise leave it alone. Parted should do this by default. Disks with 512-byte sectors do not care about alignment.

For SSD, alignment should be on 1M boundary to line up with erase blocks.

If anything in the warning uses the words "track" or "cylinder" then it can be safely ignored unless your disk is 25 years old.

kox444 · 04-04-2014, 12:46 PM

Yes it is 4096 bytes per sector.

Quote:

then you should make sure the partition table has 4K alignment

How do I check it?

The warning only says "The partition is misaligned by 1024 bytes. This may result in very poor performance. Repartitioning is suggested."

Some more info from fdisk command

Code:

Disk /dev/sdb: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x00087510

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1            4094  1027133439   513564673    5  Extended
Partition 1 does not start on physical sector boundary.
/dev/sdb2   *  1027133440  1027338239      102400    7  HPFS/NTFS/exFAT
/dev/sdb3      1027338240  1232791551   102726656    7  HPFS/NTFS/exFAT
/dev/sdb4      1232791552  1953523711   360366080    7  HPFS/NTFS/exFAT
/dev/sdb5            4096     2508799     1252352   83  Linux
/dev/sdb6         2510848    10817535     4153344   82  Linux swap / Solaris
/dev/sdb7        10819584   100911103    45045760   83  Linux
/dev/sdb8       289470464  1027133439   368831488   83  Linux

rknichols · 04-04-2014, 02:05 PM

In this case, you're fine. All of the logical partitions within the extended partition are properly aligned, as are all of the other primary partitions. The only thing misaligned is the header on the extended partition itself, and that gets read just once when the system boots.

FYI, the performance hit (bad -- factor of 10 or worse) for misaligned filesystems is only for write operations. The impact on reads is negligible.

jefro · 04-05-2014, 03:50 PM

http://gparted.org/display-doc.php?n...tion-alignment if you want to follow their use.

kox444 · 04-06-2014, 04:23 AM

That's good to know. Thanks.