Work with only 3 Disks

[AmitMa]

Hi.
one of my disks is defect, so i want to work only with 3 disks. I formatted the disk using the Iomega wizard, and now I see this message in almost every page:

Disks Not Ready
The selected function is not available due to the state of the disks.
Visit the Dashboard for details.

In the dashboard the status is:
The Iomega StorCenter device failed and some data loss may have occurred.

and in the disk manager the Available Storage is 0 B.

the data protection settings is set to "Without data protection there is 2.7 TB of space for data"
Still, i can't access to shares or anything.
buy a new disk is not an option at this time.
PLZ help.

[AmitMa]

Here is the raid dump file:
RAID Information from mdadm
===========================
Output from: mdadm --detail /dev/md0
/dev/md0:
Version : 00.90
Creation Time : Mon Oct 6 18:14:51 2014
Raid Level : raid1
Array Size : 2040128 (1992.65 MiB 2089.09 MB)
Used Dev Size : 2040128 (1992.65 MiB 2089.09 MB)
Raid Devices : 4
Total Devices : 3
Preferred Minor : 0
Persistence : Superblock is persistent

Update Time : Mon Oct 6 19:09:29 2014
State : clean, degraded
Active Devices : 3
Working Devices : 3
Failed Devices : 0
Spare Devices : 0

UUID : ac6933fd:e3260a0a:23fec1b1:25e3531d
Events : 0.32

Number Major Minor RaidDevice State
0 8 1 0 active sync /dev/sda1
1 8 17 1 active sync /dev/sdb1
2 8 33 2 active sync /dev/sdc1
3 0 0 3 removed

RAID Information from mdstat
============================
Output from: cat /proc/mdstat
Personalities : [linear] [raid0] [raid1] [raid10] [raid6] [raid5] [raid4]
md0 : active raid1 sda1[0] sdc1[2] sdb1[1]
2040128 blocks [4/3] [UUU_]

unused devices: <none>

Filesystem information from dumpe2fs
====================================
Output from: dumpe2fs -h
NO drive to dump filesystem information!

[Mijzelf]

That is the raid array containing the firmware, not the data. The data array is /dev/md1, I guess.