Release Notes

PS Series capacity
23 Dell PS Series Configuration Guide
7 PS Series capacity
7.1 RAID 6 drive layouts and total reported usable storage
RAID 6 (striped set with dual distributed parity) combines N disks in an arrangement where each stripe
consists of N-2 disks capacity for data blocks and two disks capacity for parity blocks. Each parity block
generates parity using a different view of the data blocks depending on the RAID 6 implementation. RAID 6
can tolerate up to two drive failures per RAID stripe set at the same time without data loss. RAID 6 is not
recommended for workloads consisting mainly of random writes. Using a RAID 6 policy, Table 7 shows the
drive layouts that are enforced based on the number of drives in each array/hot spare configuration, and the
total usable storage available for each model.
RAID 6 drive layouts and total storage available with hot spares (in GB)
Disk drives
Hot spare
No hot spare
6
5 data/parity + 1 hot spare
6 data/parity
7
6 data/parity + 1 hot spare
7 data/parity
8
7 data/parity + 1 hot spare
8 data/parity
12
(f)
11 data/parity + 1 hot spare
12 data/parity
14
13 data/parity + 1 hot spare
14 data/parity
16
15 data/parity + 1 hot spare
16 data/parity
8 + 8
(c)
15 data/parity (d) + 1 hot spare
16 data/parity
24
(a)(f)
23 data/parity + 1 hot spare
24 data/parity
7 + 17
(e)
23 data/parity + 1 hot spare
24 data/parity
42
(a)
40 data/parity + 2 hot spare
N/A
(b)
48
(a)
47 data/parity + 1 hot spare
N/A
(b)
84
(a)
82 data/parity + 2 hot spare
N/A
(b)
a. 24, 42, 48, and 84 drive arrays implement multiple RAID 6 sets within a single chassis.
b. 42, 48, and 84 drive arrays cannot implement a no hot-spare RAID policy.
c. PS60x0 XVS with 8 x 100GB SSD and 8 x 450GB SAS.
d. One 450GB hot spare, 2 x 450 GB parity and 2 x 100GB SSD parity. In the event of a drive failure
(SSD or SAS), the RAID set is reconstructed using the 450GB SAS hot spare.
e. One 600GB hot spare, 2 x 600 GB parity and 2 x 400 GB SSD parity. In the event of a drive
failure (SSD or SAS), the RAID set is reconstructed using the 600 GB SAS hot spare.
f. PS41x0/PS61x0 and PS4210/PS6210 models only.