Drive size decreases when used in Raid 1 mirror

[Mears]

I'm using a Fasttrak 100 IDE RAID controller and I just created a mirror off of two 160GB drives. The bios utility shows both drives as being 163000MB, and after the array is created, the array shows up as 160000MB. However, drive manager in winXP shows the drive as just below 152GB. When both drives were being used independently, they each showed up as 156GB. Does anyone know why I "lost" 4GB?

 

[Zepper]

Probably some temporary housekeeping space.
.bh.

 

[Smithyoffline]

everyone loses part of the drive in formatting ect, i have 120gb hard drive that shows up as 111Gb

 

[Mears]

Well, the utility shows them as 160,000MB and when setup individually, they are 156GB. Is there really that much overhead in RAID 1?

 

[Budman]

Read the anandtech Faqs

Why doesn?t my hard drive have the advertised amount of space?