I'm a relative newbie with Linux, but fairly advanced otherwise. I previously had my media server setup with a hardware RAID card (the LSI Logic Megaraid i4) on Windows XP using Maxtor 300GB ATA drives. I recently filled my array, and have been playing around with Linux software RAID as a possible platform for my server.

The "300GB" Maxtors have a raw capacity of 283 GB. With hardware RAID under Windows XP, an NTFS formatted 7-disk RAID-5 array yielded a storage capacity of 1.67 TB. (which amounts to ~ 278 GB /disk) Also a non-raided drive yields the same 278 GB size after NTFS formatting.

Using Fedora Core 3, I created a 4-disk RAID-5 array using ext3 file system with the same 300 GB Maxtor drives. I was shocked to see my available capacity was only 783 GB (261 GB/disk). I installed the root and swap partitions on a separate system disk, so there is no usage of the array by the system. "df -h" indicates a size of 838 GB for the array, but with 1% usage and only 783 GB available? What happened to those 55 GB? Does the ext3 file system eat that much space? I was planning on running a 12-disk array ultimately, but with this difference in capacity, it is almost worth buying Windows Server 2003 and using its software RAID instead...

Any suggestions?

By default 5% of an ext3 partition is reserved for root. Having reserved space is supposed to reduce fragementation and allow root to log on in case you fill up the drive. Use tune2fs to reduce the size.

Also, see what df -H gives you, it uses different rounding of KB and MB etc to -h