RAID Array - Cluster size?

Hipnotic_Tranz · Post by **Hipnotic_Tranz** » Mon Jul 29, 2002 4:56 pm

I've been reading that the cluster size can improve/decrease performance. Since I'm rebuilding my RAID array, I was curious what cluster size I should use? I'm using an HPT370 controller with two D740x (40gig) Maxtor drives, if it matters.

[edit]
<i>"While the "/Z" switch has become increasingly popular amongst those that like to tweak their systems, I do not recommend the use of this switch. In theory, it should allow you to create a large partition with small cluster sizes, or a small partition with large clusters. The problem is that this switch creates non-standard partitions that can cause problems with some software that isn't expecting them. In the example given above, the file allocation table would have twice as many entries as normal for a FAT32 partition. There have been problems reported with programs "breaking" when attempting to use partitions that have been modified using the "/Z" parameter to make small clusters, because the programs can't handle the increased numbers of clusters in the partition. If you really care about getting smaller cluster sizes that much, just break the disk into more partitions. Using "/Z" to increase the cluster size should work, but again, it's a minor performance tweak and should be approached with caution."</i>

This is what I did before because I read it was a good thing to do, I set my drives to /z:32 if I remember correctly. Should I just keep it default and not mess with it? And what about in my HPT370 bios? It asks what 'block size' I would like to use (which I'm assuming is the same as cluster size?) and my choises are 64,32,16,8 and 4.

[edi2]
I'm now reading at this website (http://www.viahardware.com/faq/ka7/faqdisks.html) that the recommended block size for an HPT370 controller is 16 and that you should format with /z:32--twice the block size for optimum performance (this is on a KA7-100 mobo, but the controller is the same as my Epox).

NascarFool · Post by **NascarFool** » Mon Jul 29, 2002 10:29 pm

I tried 64 and 16, no difference in performance for me.

Hipnotic_Tranz · Post by **Hipnotic_Tranz** » Mon Jul 29, 2002 10:34 pm

Thats good to hear. I just kept it all default (block size 64).

...good god it takes forever to transfer all my music though. When I was going from my RAID-0 Array to my spare 15gig drive, it only took about 12 minutes for 13gig. I'm going the other way around and it has been several hours and it still isn't done

Busby · Post by **Busby** » Mon Jul 29, 2002 10:53 pm

File system cluster size? I haven't noticed a difference. RAID Stripe size? Oh yeah a big difference between 16K and 32K.

Hipnotic_Tranz · Post by **Hipnotic_Tranz** » Tue Jul 30, 2002 1:31 pm

Is 'raid stripe size' the same as 'block size'? And was it better having 32k or 16k? Like I said, I kept it default at 64k and things seem to be slower as of now. I mean, it took about 3 minutes to copy 450mb. I'm hoping it's just because I haven't installed the Highpoint device drivers... ....cause I would kill myself if i had to rebuild my array now

Busby · Post by **Busby** » Tue Jul 30, 2002 5:16 pm

Did you rebuild your array? If so then it's stripe size and 64k is a good performer depending on your drives and controller. It all depends on the drives and controller. I don't see a regular everyday difference between 16K and 64K (turns out it was 64k), only when benchmarking.

Speck102 · Post by **Speck102** » Wed Jul 31, 2002 12:57 am

Hey guys, I also have a question about raid. I have a 60gig and a 30gig HDD, now my question is why do I end up with 15gigs. I know they are both not the same size, and I plan on fixing that when I get some extra cash, but I ended up with 15gigs when I had the 30gig and an 8gig hoked up. I'm a bit lost here and would appreciate some help

Busby · Post by **Busby** » Wed Jul 31, 2002 7:05 am

8+8 = 16, you never get the whole advertised space.

As for 15GB with the 60 and 30, i have no clue. It should be 60GB.