Hard Drive Format Blocking Factor

I've formatted six new internal SATA II drives in my MacPro and every time it asks me to select a blocking factor. As I recall, it defaults to 32. I'm using most of my non-boot drive space for photography images, mostly RAW files.

What is this about?

How do I evaluate what number to select for formatting?

I've never had it ask me anything like that.
Can you upload a screen shot?

Are you formatting HFS+ Journaled?

Edit: You're setting up a RAID array, aren't you? I think you pick the block that fits the type of file you're using. I don't know how you determine that. I chose the default and it worked quite well.

Here's what Apple says:

Selecting options for your RAID set

To optimize storage performance of a RAID set, you can set the storage block size used by the disks in the set to match the size of data stored on the set. You should select these options at the time you create a RAID set.

For example, a database might store small units of data so a small block size might be best for the RAID set. A video processing application might require fast throughput of large amounts of data, so a larger block size might be best for the set.

You can also set up a mirrored RAID set to automatically rebuild the set in the event of lost or damaged data. Choosing this option also allows you to easily add additional or "spare" hard disks to your mirrored set as replacements.

Click to expand...

That's what I'm seeing

Thanks for posting the Apple description Aptmunich. That's what I've seen when formatting internal RAID-5 sets.

Many of my files are initially RAW images around 13mb. If that's the case, perhaps I should reduce the block size to 16mb. RAW images, TIFF and Photoshop files can vary greatly though. A few of my Photoshop files are over 400mb after editing.

Even with the MacPro, performance seems be an issue with large files. Even with 9gb RAM, I'm still using a lot of scratch disk space. I set up a 20gb dedicated internal scratch partition, but response is still slower than I'd like. I know that mirroriing is slowing things down to some degree. I've wondered if a PCI-E RAID controller with an external hard-drive case would provide better performance.

Oops - Raid-1

I should have said RAID-1 (mirrored), not RAID-5.
I'm considering RAID-5 when I go to an external drive enclosure.

You're using 6 HD's? Why not setup a RAID 0 for two of them (OS and apps disk) so you can work fast when using Photoshop. And setup the rest as desired for backup and storage. There is a RAID 1+0 and a RAID 0+1 configuration I read in the wikipedia article.

It sounds like you need to be using the largest size blocks though, 128k, right?

bryphotoguy said:

You're using 6 HD's? Why not setup a RAID 0 for two of them (OS and apps disk) so you can work fast when using Photoshop. And setup the rest as desired for backup and storage. There is a RAID 1+0 and a RAID 0+1 configuration I read in the wikipedia article.

It sounds like you need to be using the largest size blocks though, 128k, right?

Click to expand...

I recently replaced an internal mirrored 500gb drive set with mirrored 1tb drives. A larger block might be the right thing to do but I will need to offload 500gb to my spare internal drive and reformat the 500gb RAID drives. It takes quite awhile to copy all that data for uncertain improvements with 128kb blocking but I'll do it.

An Adobe workshop speaker at last weeks NAPP (Nat'l Assn of Photoshop Professionals) talked about measuring Photoshop response with a stopwatch or internal timer. He had charts showing performance differences with RAID 1+0 or 0+1 and surprisingly, this didn't always improve speed. I need to do the testing with my system and files to see my performance options. Of course, that means more external drives to offload data, reformatting, constructing new RAID sets, etc. I'll probably put this off until I get that external drive box with extra space to play with. Isn't this fun ?

Sounds like a blast.

I set up my old Mac Pro using RAID 0 with a pair of 250GB drives. I didn't notice much of a boost when transferring files but from a DVD, the transfer was cut down from 12 minutes to 9.
It was certainly not fun transferring files back and forth. 100GB transfers took an hour or so.
I was thinking of purchasing a matching 750GB drive to do a mirrored setup but after reading your story, maybe I'll just let Time Machine do its thang.

Good luck.

The question is then, Are you saving any time by doing all this testing/ formatting/ transferring?