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As new drives with 4096b sized blocks appeared, partition alingment is becoming more and more important.

But, what I am interested in is, if I use the whole block device for filesystem (eg. /dev/sdc) - are the FS block aligned, or do I need to create a partition and align it for FS to be aligned with block device sectors?

My logic tells me that it's OK, because aligment is needed in first place because of MBR and/or partition table, which takes some space at the start of the drive. If I don't use it, my FS should be aligned by default.

Am I correct or am I missing something?

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Not having partitions is like having a partition starting at sector 0 which is aligned (unless you have something crazy like an off-by-1 offset jumper for old OS that start at sector 63, in which case you'd have the same alignment issues with partitions...).

With a partition table, making a partition that starts at 0 is usually not possible since that's where the MBR / partition table itself resides.

I recommend to use partitions even if you don't think you need to, since a partition table makes it clear to installers, bootloaders and the like, that this disk is in use and how. It's easy to have accidents with unpartitioned disks.

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