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Disk Allignment

wobbe
Respected Contributor

Disk Allignment

When you install Linux on a HP server with a smartarray controller are partition automatically aligned correctly?
For windows I assume this is done correctly through the smartstart installation process but what about all those different linux installers?


3 REPLIES
Kranti Mahmud
Honored Contributor

Re: Disk Allignment

Hi wobbe,

During POST, you can perform the disk alignment using F8....

Rgds-Kranti
Dont look BACK as U will miss something INFRONT!
wobbe
Respected Contributor

Re: Disk Allignment

You are probably talking about the raid configuration. as far as I know that has nothing to do with the partition alignment.

Matti_Kurkela
Honored Contributor

Re: Disk Allignment

No idea abut "all those different linux installers". Probably only the very latest enterprise distributions might do it. RHEL 5 certainly does *not* do it yet.

Alignment is not a significant issue if you're setting up RAID 1 (i.e. mirroring), since everything is written to both disks anyway.

If you set up RAID 0 or RAID 5, then alignment becomes an important question... but my opinion is that running RAID 0 on system disks on a production server is just asking for trouble, and RAID 5 would be best used on data disks only.

However, since most Linux installers offer console access while the installer is running, it should be easy enough to do the partitioning manually, to implement the correct alignment options, if you choose to run your system on SSD, RAID 0 or RAID 5... or if you're planning scripted installations, this should be programmed as a pre-installation script.

Here's a blog post that includes instructions for setting up 128k alignment for partition, LVM and filesystem levels:

http://thunk.org/tytso/blog/2009/02/20/aligning-filesystems-to-an-ssds-erase-block-size/

If you set up your data disks as LVM-on-raw-disk, the first extent will be aligned to 192kB boundary by default. As the default extent size is 4 MB, the raw LVM default layout will be compatible with 4kB alignment at the LVM level.

MK
MK