2TB 4k Sector HDD (Samsung HD204UI) exposes 512B sectors

EliasP

I've recently bought 2 Samsung 2TB HDDs (Spinpoint F4, HD204UI).
These are AFT disks, which have 4k sector sizes, but it seems like the HDDs only expose 512b sectors to the OS:

gorkypl · Guru Joined: 04 Oct 2010 Posts: 444 Location: Kraków, PL

Yeah, I've got one - the lies about physical 512b are quite disappointing, but I have to admit that the disk itself is really fast and cool.
Unfortunately I can't help you, because I'm using it only with LVM, no RAID - and placing LVM on well aligned (starting on 2048s) partition seemes to be enough, as LVM uses quite large chunks of data (like 1MB or so). But when I was googleing while installing it in my system I've found an article which may help in some way (albeit the author doesn;t seem to be concerned of what he writes):
http://blog.bigsmoke.us/2010/05/13/aligning-partitions-with-raid-and-lvm-on-drives-with-4-kb-sectors

EliasP · Posted: Sun Mar 20, 2011 3:37 am Post subject:

So what he did, was using a partition on each disk which was 4k aligned.

I'll probably end up doing this too, as it looks, like it's the most simple solution to work around this vendor stupidity.

s_bernstein · Posted: Sun Mar 20, 2011 7:33 am Post subject:

The problem is, that the WD Green Caviar 2TB also reports 512B sectors to the OS. So maybe the best way is to go with a 3TB disc because they can't report 512B blocks.

Hu · Administrator Joined: 06 Mar 2007 Posts: 23193

Even though the drives report wrong information about their internal design, that only causes the kernel to pass the misleading data to user tools. If you use a tool, such as sfdisk, which can set layout on arbitrary sectors, then you can partition the device with any layout you want. You may need to use --force, and you will need to work out the "correct" layout on your own, since sfdisk is not told that its default is a bad idea.