IDE RAID0 Block & Cluster sizing.

[littlee]

Hello all.

I'm a tad pedantic when it comes to optimizing my raid array. And since I'm upgrading my puter to a xp 1700+ (from a p3 733) I thought it was time for a rebuild.

I've read the RAID guide here and it's the best one I've seen as of yet Here. It gives good advice as to block sizing however nothing when it comes to cluster sizes in OS's.

I'm going to try 8,16,32, and 64kb block sizes on the weekend as see how fast the OS (w2k) loads and how much disk activity I get. (Only visual observations as I'm mainly intrested in decreasing startup time).

My question is to cluster sizing. Microsoft recommends 4kb clusters for >2gb NTFS partitions (which coincidently is default) and W2k has problems with anything over 4kb in size (read: Defrag won't work, apparently recycle bin doesn't either, nor does compression). XP on the otherhand, can handle upto 64kb clusters. I don't mind wasting space, and MS says small cluster sizes increase fragmentation...

So how do I install XP on my raid array with a different cluster size? Do I have to format the array (via another computer) then install XP on it? And does this also help place the MFT at the front of the array? As I think that's what I had to do with w2k (but didn't)..

Cheers..

Little Erve.

 

[Nothinman]

W2k has problems with anything over 4kb in size (read: Defrag won't work, apparently recycle bin doesn't either, nor does compression). XP on the otherhand, can handle upto 64kb clusters.

Where did you read that? I'd be very surprised if they made major changes to the filesystem code between Win2K and XP, very little has changed elsewhere in them.

None of the installs let you pick the cluster size, you would have to format it before hand with something like PQMagic.

Honestly all the speed difference you're going to get will be negligable, I would be surprised if you could even notice a difference between 4k and 64k clusters, other than the massive loss in free space =)

 

[littlee]

Yes i'm being pedantic. It's what I do best

Technet is your friend..
Microsoft Article

Also here's an intresting one about NTFS performance.
Optimising NTFS

Oh and partition magic v7 can't resize NTFS partitions apparently link

That part about the recycle bin was actually from tech support @ diskeeper.. here's the email.

I have an NTFS partition with a cluster size larger than 4K. Why won't Diskeeper work?
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NTFS does not fully support cluster sizes larger than 4K. You can see this by trying to set your cluster size higher than that in the Disk Administrator GUI if you are using Windows NT 4.0. Diskeeper uses the defrag API of Windows NT 4.0 and Windows 2000 which does not support a cluster size of over 4k, thus we are bound to follow those constraints. You will also not have use of the Recycle bin or file compression with a cluster size larger than 4k.

This 4k cluster size limitation has been increased to 64k in Windows XP and as a result Diskeeper 7.0 will defragment XP disks with cluster sizes up to 64K

The part about not moving files smaller the 16 clusters in size, I am not aware that the built in defragger has such a limitation but I'll take your word for it.

With a cluster size of 4K the smallest file on your system will by 4K in size. Diskeeper can and will move these small files.

 

[littlee]

I think what i'll try is imaging my raid array and changing the block size to all possible combinations (1/2/4/8/16/32/64/128/256/512/1024Kb's) and time it(manually with a stop watch) from boot to windows load (i.e. when the HDD led stops blinking) Crude but i'm not sure of any other way to time it. Then I'll set the block size to the fastest one I find and setup an unattended install of XP and test several different cluster sizes (might take a while I guess, I'd better start early).

I must make sure I write down all my findings

 

[irrigating]

Your RAID array is a stripe set, "0"? Try setting your stripe size to double whatever your cluster size is. If you want 4kb clusters, I think your optimum stripe size in RAID 0 would be 8kb. The CPU usage will be inversely proportional to the stripe size. At 64k stripe size, usage might be 2%. At 32, it would be 4%, ect. This is what I got trying different settings in fat32. I'd be interested to see what your results are on NTFS.