February 4, 2006

Setting the sector size - why 4 KB?

Microsoft gives the scoop in Windows NT Boot Process and Hard Disk Constraints. Here's the skinny. The partition table which Windows uses to track hard disk partitions has a field size of 32-bits. The number of sectors in a partition is thus limited to 2^32 = 4,294,967,296. The rest is multiplication: a 4KB sector size permits a maximum partition size of 4*1,024 bytes*4,294,967,296 = 17,592,186,044,416 bytes = 16 TB. The next sector size down, 2KB, permits a 8 TB partition. Hmm, I think I could have chosen a 2KB sector size.

Posted by torque at 9:02 PM | Comments (0) | TrackBack

A few tips on setting up a 7.5 TB array - the Vtrak m500p

You read that correctly - that's 7.5 TB, as in terabyte. Yowsas... Configuration: Dell 1800, Adaptec 39320 Ultra320 SCSI card, Vtrak m500p. Here are the tips:

  1. When you initialize, select 4 kilobyte sectors, rather than the default 512 bytes. Windows can support huge disk sizes, but there is a limit to the number of sectors it can handle.
  2. Make sure to set Target ID and Lun ID in the WebPAM. I left it at the default - blank - and was unable to read the drive in Disk Manager.
  3. After setting the Target ID and Lun ID, you should be able to initialize the disk. Use GPT! (Otherwise, you'll only get a fraction of your storage.)
  4. You might timeout trying to format the drive. If so, take the SCSI speed down to 160 MBps if you are at 320. That did the trick for me - then step it back up to 320 when you start using it*.
*Yes, that makes me nervous.

Posted by torque at 8:41 PM | Comments (1) | TrackBack