To calculate the total physical capacity of a DS6000™ storage unit, multiply each disk drive set feature (4
identical disk drives with the same capacity and rpm) by its total physical
capacity and sum the values.
The logical configuration of your DS6000 series storage affects the effective capacity of the disk drive set.
Specifically, effective capacities vary depending on the following:
- Data format
Physical capacity can be logically configured as fixed block
(FB) or count key data (CKD). Data accessed by open systems hosts or Linux
on System z that support fibre channel protocol must be logically configured
as FB. Data accessed by zSeries hosts with z/OS or z/VM must be configured
as CKD.
- Array or rank configuration
The disk drive arrays on the system can
be combined in various ways into RAID ranks and RAID configurations. One or
more arrays can be combined to create a single contiguous storage space called
a RAID rank.
Each RAID rank is divided into equal-sized segments known
as extents. All extents are approximately 1 GB. However, FB extents are slightly
larger than CKD extents.
Table 1 and
Table 2 list the effective capacity
of DS6800 disk drive sets.
Table 1. Disk drive
set capacity (RAID 10 arrays)| Disk size (GB)
(See Note 2) |
Total physical
capacity per (GB) disk drive set (See Note 3) |
Fixed
block (FB) or count key data (CKD) |
Effective capacity in GB
(Number of Extents, see Note 1)
|
|---|
| Ranks of RAID
10 arrays |
|---|
| 1 + 1 (See
Note 4) |
2 + 2 (See
Note 5) |
3 + 3 (See
Note 6) |
4 + 4 (See
Note 7) |
|---|
| 73 |
292 |
FB |
67.57
(62)
|
136.06
(127)
|
204.01
(190)
|
272.73
(254)
|
| CKD |
64.33
(68)
|
135.28
(143)
|
201.50
(213)
|
268.67
(284)
|
| 146 |
584 |
FB |
136.37
(127)
|
275.32
(256)
|
414.46
(386)
|
552.98
(515)
|
| CKD |
134.33
(142)
|
271.50
(287)
|
408.67
(432)
|
545.85
(577)
|
| 300 |
1200 |
FB |
281.32
(262)
|
561.27
(523)
|
845.03
(787)
|
1125.28
(1050)
|
| CKD |
275.293
(291)
|
555.31
(587)
|
832.48
(880)
|
1110.61
(1174)
|
| 500 |
2000 |
FB |
( ) |
( ) |
( ) |
( ) |
| CKD |
( ) |
( ) |
( ) |
( ) |
Notes: - All values for capacity and extent numbers are based on preliminary data.
- Physical capacities are in decimal gigabytes (GB). One decimal
GB is 1 000 000 000 bytes.
- Although disk drive sets contain 4 drives, arrays use either 4 or 8 drives.
- The array consists of 1 data drive that is mirrored to 1 copy drive. Two
other drives in the disk drive set are used as spares.
- The array consists of 2 data drives that are mirrored to 2 copy drives.
- The array consists of 3 data drives that are mirrored to 3 copy drives.
Two other drives in the disk drive set are used as spares.
- The array consists of 4 data drives that are mirrored to 4 copy drives.
|
Table 2. Disk
drive set capacity (RAID 5 arrays)| Disk size
(GB) (See Note 2) |
Total physical
capacity (GB) per disk drive set (See Note 3) |
Fixed
block (FB) or count key data (CKD) |
Effective capacity in GB
(Number of Extents, see Note 1)
|
|---|
| Ranks of RAID
5 arrays (See Note 4) |
|---|
2 + P
(See
Note 5)
|
3 + P
(See
Note 6)
|
6 + P
(See
Note 7)
|
7 + P
(See
Note 8)
|
|---|
| 73 |
292 |
FB |
136.06
(126)
|
204.01
(190)
|
410.17
(382)
|
477.82
(445)
|
| CKD |
135.28
(141)
|
201.50
(212)
|
404.89
(427)
|
473.00
(499)
|
| 146 |
584 |
FB |
275.32
(256)
|
414.46
(385)
|
830.00
(773)
|
968.52
(902)
|
| CKD |
271.50
(287)
|
408.67
(432)
|
820.19
(866)
|
956.41
(1010)
|
| 300 |
1200 |
FB |
561.27
(524)
|
845.03
(787)
|
1692.22
(1576)
|
1972.46
(1837)
|
| CKD |
555.31
(587)
|
832.48
(881)
|
1669.70
(1765)
|
1947.83
(2059)
|
| 500 |
2000 |
FB |
(877) |
(1316) |
(2634) |
(3071) |
| CKD |
(982) |
(1474) |
(2950) |
(3440) |
Notes: - All values for capacity and extent numbers are based on preliminary data.
- Physical capacities are in decimal gigabytes (GB). One decimal
GB is 1 000 000 000 bytes.
- Although disk drive sets contain 4 drives, arrays use either 4 or 8 drives.
- In RAID 5 configurations, the parity information uses the capacity of
one disk but is actually distributed across all of the disks within the array.
- The array consists of 2 data drives and 1 parity drive. One other drive
is used as a spare.
- The array consists of 3 data drives and 1 parity drive.
- The array consists of 6 data drives and 1 parity drive. One other drive
is used as a spare.
- The array consists of 7 data drives and 1 parity drive.
|
To estimate the usable storage capacity
of a
DS6000 storage
unit, it is helpful to understand the rule of sparing disks.
- Each switched FC-AL loop will have up to two spares.
- The base frame will have one or two spares: one spare in 8 DDM configurations
and two spares for other configurations. You may have three spares if your
configuration is RAID-5 on 8 drives and then RAID-10 on 8 drives on the first
enclosure for the loop.
- The first expansion frame is the second loop and will have one or two
spares.