RAID 5 stripe size set at 128KB. What's the recomended NTFS cluster size?

[smartins]

Ok, I just finished initializing a 4 500Gb disk raid 5 array with a 128KB stripe size, as recommended by the controller (Areca 1261ML) vendor.

Now it's time to create a volume in windows and I've used Windows Removable Storage to create a logical unit with the full size (1.5 TB for now, will grow over 2 TB soon).

While creating the ntfs partition I was asked what ntfs cluster size I wanted to use, Default or a selecting of several others. Default used a 4KB one but now I'm wondering if this cluster size should or should not be bigger, or equal to the array stripe size.

Anyone can help me out with this question?

Thanks,
Steven

[mwarps]

I had read a while back (years) that making the cluster size the same as the stripe size was your best bet, but that was for RAID0. If you have a 128K cluster size and work with small files, you're going to have a shit ton of wasted space.

[Eickst]

What's the average file size look like? If this is for media files like audio/video and iso's I would set the stripe size even higher than 128k.


Quoted from storage review post that is no longer up on the web

Smaller stripe sizes improve STR of smaller files at the expense of service times (similar to "access time") for 2 or more randomly positioned/accessed files. The larger the stripe size, the greater the probability that any two files will be on opposite drives in their unstriped form, thus facilitating concurrent access to them. This improves multitasking ability and service times of multiple random I/O requests (even at lower I/O queue depths) at the expense of small file average STR.

Here's another link..

http://storageadvisors.adaptec.com/2006/06/05/picking-the-right-stripe-size/

Oh and don't confuse cluster size with stripe size. The OS doesn't know it's writing to a RAID, the clusters and stripes don't line up, so having a 4KB cluster size does not waste 124kb of your stripe. Having a 128KB cluster and writing a 4KB file will waste 124KB of your space.

I say use a cluster size of 64KB.

[smartins]

What's the average file size look like? If this is for media files like audio/video and iso's I would set the stripe size even higher than 128k.


Quoted from storage review post that is no longer up on the web



Here's another link..

http://storageadvisors.adaptec.com/2006/06/05/picking-the-right-stripe-size/

Oh and don't confuse cluster size with stripe size. The OS doesn't know it's writing to a RAID, the clusters and stripes don't line up, so having a 4KB cluster size does not waste 124kb of your stripe. Having a 128KB cluster and writing a 4KB file will waste 124KB of your space.

I say use a cluster size of 64KB.

Thanks for your answer and the link.

This storage will be mainly for media files (tv shows, movies) for storage and streaming. A small part will be for music, photos and backups but I guess 90+% will be used by files between 350, 700 MB and even some 4.4 Gb.

I currently have mine at 128 Kb for the stripe (highest possible on this controller) and 4 KB for the NTFS cluster. I might then increase the NTFS cluster a bit more to 8 KB or even all the way up to 64 KB (if possible).

[Eickst]

In that case I would rebuild the array with an even larger stripe size. You have a REALLY nice controller, it probably goes up to 4096 stripe size. The best way to determine the best stripe size however is to test them all with your setup. That takes days, you may not want to do that but it pays off in the long run.


Good luck, sounds like you are well on your way to having a serious storage server. (All those ports and with 1TB drives coming soon.... mmm mm good.)

keep in mind that some third party disk tools don't like large cluster sizes. I think a cluster size of 256k is possible under NTFS, but I usually don't mess with it too much. i don't have a possible 8TB array on my hands though.