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Help in Aligning SSD, Vertex 2 (60gb) Raid 0, Dual boot Linux/Windows7

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December 17, 2010 8:51:45 PM

Hi all,

I just purchased 2 Vertex 2 SSDs running Raid 0. I only have the Intel Raid (P55, ICH10R) to use these. I don't care much about TRIM as I reformat every 6 months and I will not fill the SDDs anyway. I also have a separate set of HDDs 1TB (also running Raid 0).

When I built my RAID 0 array, I didn't use all of the space. I only used 90GB and made the rest as spare (20gb) for Garbage collection. Also, I used 128kb stripe.

So my usable space will only be 90gb. I haven't partitioned it yet. I plan to partition it into 2. 1st partition will be Windows7 (70gb). The 2nd partition would be Ext4 (20gb). I'm not going to use any swap partition. So it will be like this:

Partition 1: 70gb Windows 7
Partition 2: 20gb Ext4 / Linux Mint

I've had little experience with aligning SSDs but from a netbook (XP). I use diskpart and the parameter "align=1024".

This is my first time aligning in Raid 0 and I don't know what to do.

I still plan to partition my Raid 0 SSD using Diskpart in Win 7 because I don't want the 100mb partition Windows automatically creates.

I know I can partition the Windows 7 easy but how will I partition and align my 30GB for Linux. Will Gparted automatically align this too? Should I use fdisk to align it ALONG side my already aligned (1024kb) Windows 7?

There are a lot of guides I could find but it only shows aligning Linux. If there is a dual boot guide alignment, the guide only uses 1 SSD, not RAID 0. I also found out that usually Linux alignment is suggested to be 512kb. Will it conflict if Windows 7 is aligned at 1024kb then Linux at 512kb?

Or is it better to just set the partition using fdisk instead of diskpart?

Thank you so much!
December 20, 2010 9:24:12 PM

If it was me, I'd buy another SSD for my Linux part.

But, if that is not possible, I don't see why Linux can't format it normally if you use a distro with a recent kernel.

Good question, though.

I think you should try A) recent distro or download one of the Partition Manager distros such as
B) System Rescue CD

The recent distros apparently included compatibility with alignment issues and should align the partitions when you format. Also, make sure the kernel is at least 2.6.35 or later. I think most of the recent revisions to the Partition Live CDs are at least at that kernel. For e.g., latest System Rescue CD, Parted Magic etc.

Try those and then do a data transfer test (test reads and writes) and see how close they are to the specs given by your SSD manufacturer. For the OCZ, I guess it's around 270/280. I don't know about RAID and SSDs....sounds complicated. I doubt RAID in SSDs has really matured much and seems like a lot of trouble to keep tabs with. I would keep things simple but that's just me.
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December 21, 2010 12:42:51 AM

If previous partitions are aligned then any following partitions should also be aligned unless you force it otherwise. I think you'll need to tell gparted to align to the MB and not the cylinder, but I'm not entirely sure. Of course you could just use the Disk Management tool in Windows 7 (accessed via Computer Management - search for it in the start menu). It should create all new partitions right after the previous one which means they will be aligned. As long as you only format them in Linux rather than recreating them you'll have no issues.
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