RAID Arrays:
Primary, SAS/SATA RAID 0+1, totalling 12TB in operation; 10.9TB after formatting, using eight 3TB WE RE3 drives (24TB / 2 for RAID-1) = ((12TB))
Secondary Arrays: 5x3TB WE3 drives, as RAID-5 (12tb); 4x 1TB 2.5" Drive RAID (4TB); 250GB RAID-1; 3.5TB RAID-5 = ((19TB, 750GB))
Hot Spares: 2x 3TB WE3; 2x 500GB ATA133; 1x 73GB SAS 15K; 1x 146GB SAS 10K. = ((7TB, 219GB))
System RAID: 1TB RAID-1 (1TB); 80GB RAID-1; 500GB RAID-1; 146GB SAS 15K RAID-0 = 1,750GB ((1TB 726GB))
SCSI-3: 4x 73GB SCSI-3 15K RPM; 2x 143GB SCSI-e 15K RPM. = 572GB
JBOD Volumes: 2x750GB (1.5TB) System Drives in FMG5-1; 1x 2TB WE3 Drive in FMG5-2 (2TB); 4TB WE3 Data Volume; 2x1TB Data Volumes = 9.5TB
NAND: 3x 8GB; 2x16GB; 12x 32GB; 4x 64GB; 5x 128GB = 1,328GB (1TB, 304GB)
(((43TB, 1,023GB))) * .9 = ~40TB Formatted, leaving out drives that are not in use, and laptop HDDs, and space used up in RAID-1 and RAID-5 sets for mirror, and parity.
I have a gigantic media archive, plus graphic design (for print), server mirrors, system mirrors, and the like. Everything is mirrored at lest one time, so my total usable capacity is halved again, to about 20TB, of which, about 35% is video. Keep in mind that I need to keep several system images of the running servers on hand, which tend to be 500GB to 1TB files (per image). At present, I have between 7 and 10Tb used, just by those system images, and that does not include shared media such as video, as that is not mingled with user accounts, but isolated onto non-system RAID arrays.
I still remember when a 10MB HDD was gigantic. My, how things have changed.
'Too much space' is a fallacy. :/
I run servers, including streaming media servers, so this isn't purely for my own satisfaction. 95% of the disc media is enterprise rated, and the remainder is NAND or some small SATA or ATA drives.