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6 × 22 TB in RAID 6

Usable space, rebuild time and read error risk for 6 drives of 22 TB each.

6 × 22 TB drives in RAID 6 give 88 TB of usable space, which Windows shows as 80 TB. 44 TB goes to parity, so 67% of the 132 TB raw space is usable. The array survives any two failed drives, and it is still protected while one drive rebuilds.
TB

Size printed on the drive label. Different sizes? The array uses the smallest one for every drive.

Advanced settings
MB/s

Typical hard drive: 100–200 MB/s with no other load. SSD: 400 MB/s or more.

From the drive datasheet. It is a worst-case spec, so real drives usually do better.

Show capacity in
88TB usable

Array healthy
Your data Parity or mirror copy Failed drive Click a drive to make it fail.
Drawing6 × 22 TB in RAID 6
Raw132 TB
Efficiency67%

Drives that can fail

Rebuild of one drive

Read error during rebuild

Checks for this setup

The same drives in every RAID level

6 drives of 22 TB each.

LevelUsableEfficiencyDrives that can failRebuildRead error in rebuild
132 TB
100%
None
—
—
22 TB
17%
Any 5
40 h
Fixed by another copy
110 TB
83%
Any 1
40 h
59%
88 TB
67%
Any 2
40 h
Fixed by parity
66 TB
50%
1 to 3
40 h
16%
88 TB
67%
1 to 2
40 h
30%
Needs at least 8 drives

6 × 22 TB in RAID 6: the numbers

Usable space88 TB (80 TB in Windows)
Raw space132 TB
Used for protection44 TB
Efficiency67%
Drives that can failAny 2
Rebuild at 150 MB/s40 h
Rebuild at 50 MB/s (busy)5.1 days
Data read during rebuild110 TB
Read error risk, desktop drivesover 99% (corrected)
Read error risk, NAS drives59% (corrected)

Rebuild

Replacing a failed drive means writing a full 22 TB drive. At 150 MB/s with no other load that takes about 40 h; on a busy array running at 50 MB/s, about 5.1 days. The rebuild reads every surviving drive: 110 TB in total.

Read errors

Reading 110 TB, the chance of at least one unreadable sector is over 99% with desktop drives (1 per 1014 bits) and 59% with NAS drives (1 per 1015). The second parity corrects it, so the rebuild finishes without losing data.

Our take

For 22 TB drives this is the setup most administrators would choose: the rebuild takes 40 h, and the array stays protected the whole time.

Similar setups

7 × 22 TB in RAID 6More drives: 110 TB usable5 × 22 TB in RAID 6Fewer drives: 66 TB usable6 × 24 TB in RAID 6Bigger drives: 96 TB usable6 × 20 TB in RAID 6Smaller drives: 80 TB usable6 × 22 TB in RAID 5Same drives: 110 TB usable6 × 22 TB in RAID 10Same drives: 66 TB usable

All RAID 6 setups

Usable space in TB. Pick a cell for the full numbers.
Drives2 TB4 TB6 TB8 TB10 TB12 TB14 TB16 TB18 TB20 TB22 TB24 TB
4 drives4812162024283236404448
5 drives61218243036424854606672
6 drives81624324048566472808896
7 drives102030405060708090100110120
8 drives1224364860728496108120132144
10 drives163248648096112128144160176192
12 drives20406080100120140160180200220240