The effective storage capacities of IBM DASD devices vary, depending on how the devices are being used. The database manager uses VM DASD block I/O services for managing DASD space for the directory minidisk, the log (or logs), and the storage pool minidisks (dbextents). The log and dbextent minidisks are managed with 4 kilobyte blocks. The directory minidisk uses 512-byte blocks.
The following figure indicates how many 512 and 4 096 byte blocks can
be allocated on a CMS minidisk. The first number is the number of
usable blocks, and the number in parentheses is the total number of
blocks. The difference between the two numbers is the blocks that CMS
allocates for its file management.
Table 39. Number of Usable Blocks on Types of CMS Minidisks
|
Device |
Cylinders or Blocks for Each Volume |
4 096-byte Blocks for Each Cylinder |
4 096-byte Blocks for Each Volume |
Ratio of 512-byte to 4096-byte |
512-byte Blocks for Each Volume |
|---|---|---|---|---|---|
|
3375 |
959 |
96 |
91,960 (92,064) |
40/8 |
456,462 (460,320) |
|
3380 J |
885 |
150 |
132,602 (132,750) |
46/10 |
605,531 (610,650) |
|
3380 E |
1,770 |
150 |
265,214 (265,500) |
46/10 |
1,211,076 (1,221,300) |
|
3380 K |
2,655 |
150 |
397,827 (398,250) |
46/10 |
1,816,621 (1,831,950) |
|
3390-1 |
1,113 |
180 |
200,122 (200,340) |
735/180 |
811,205 (818,055) |
|
3390-2 |
2,226 |
180 |
400,254 (400,680) |
735/180 |
1,622,418 (1,636,110) |
|
3390-3 |
3,339 |
180 |
600,387 (601,020) |
735/180 |
2,433,631 (2,454,165) |
|
3390-9 |
10,017 |
180 |
1,801,177 (1,803,060) |
735/180 |
7,300,915 (7,362,495) |
|
3370-1 |
558,000 |
N/A |
69,667 (69,750) |
8/1 |
553,321 (558,000) |
|
3370-2 |
712,752 |
N/A |
88,993 (89,094) |
8/1 |
706,780 (712,752) |
|
9332-400 |
360,036 |
N/A |
44,948 (45,004) |
8/1 |
357,018 (360,036) |
|
9332-600 |
554,800 |
N/A |
69,268 (69,350) |
8/1 |
550,149 (554,800) |
|
9335 |
804,714 |
N/A |
100,433 (100,588) |
8/1 |
797,974 (804,714) |
|
9336-010 |
920,115 |
N/A |
114,885 (115,014) |
8/1 |
912,411 (920,115) |
|
9336-020 |
1,672,881 |
N/A |
208,883 (209,110) |
8/1 |
1,658,881 (1,672,881) |
|
9336-025 |
1,672,881 |
N/A |
208,883 (209,110) |
8/1 |
1,658,881 (1,672,881) |
|
9345-1 |
1,440 |
150 |
215,767 (216,000) |
123/30 |
878,183 (885,600) |
|
9345-2 |
2,156 |
150 |
323,056 (323,400) |
123/30 |
1,314,843 (1,325,940) |
|
0671 |
574,560 |
N/A |
71,735 (71,820) |
8/1 |
569,743 (574,560) |
Table 40 and Table 41 show the capacities of IBM devices for
storing log and dbspace pages (dbextent space). Table 42 and Table 43 show the capacities for storing directory
information.
Table 40. Log and Dbextent Storage Capacities of IBM Count-Key-Data DASDs
| DASD Type | Number of Cylinders | Tracks for Each Cylinder | Megabytes for Each Cylinder | Megabytes for Each Volume |
|---|---|---|---|---|
| 3375 | 959 | 12 | 0.3749 | 359 |
| 3380 J | 885 | 15 | 0.5858 | 518 |
| 3380 E | 1,770 | 15 | 0.5858 | 1,036 |
| 3380 K | 2,655 | 15 | 0.5858 | 1,555 |
| 3390-1 | 1,113 | 15 | 0.7031 | 782 |
| 3390-2 | 2,226 | 15 | 0.7031 | 1,565 |
| 3390-3 | 3,339 | 15 | 0.7031 | 2,347 |
| 3390-9 | 10,017 | 15 | 0.7031 | 7,041 |
| 9345-1 | 1,440 | 15 | 0.5858 | 843 |
| 9345-2 | 2,156 | 15 | 0.5858 | 1,262 |
Table 41. Log and Dbextent Storage Capacities of IBM FB-512 DASDs
| DASD Type | Megabytes for Each Volume | 4 Kilobyte Pages for Each Volume |
|---|---|---|
| 3370-1 | 272.4 | 69,750 |
| 3370-2 | 348.0 | 89,094 |
| 9332-400 | 175.7 | 45,004 |
| 9332-600 | 270.8 | 69,350 |
| 9335 | 392.9 | 100,589 |
| 9336-010 | 449.2 | 115,014 |
| 9336-020 | 816.8 | 209,110 |
| 9336-025 | 816.8 | 209,110 |
| 0671 | 280.5 | 71,820 |
Table 42. Directory Storage Capacities of IBM Count-Key-Data DASDs
| DASD Type | Number of Cylinders per Volume | Tracks for Each Cylinder | Megabytes for Each Cylinder | Megabytes for Each Volume |
|---|---|---|---|---|
| 3375 | 959 | 12 | 0.2343 | 224 |
| 3380 J | 885 | 15 | 0.3295 | 291 |
| 3380 E | 1,770 | 15 | 0.3295 | 583 |
| 3380 K | 2,665 | 15 | 0.3295 | 874 |
| 3390-1 | 1,113 | 15 | 0.3645 | 405 |
| 3390-2 | 2,226 | 15 | 0.3645 | 811 |
| 3390-3 | 3,339 | 15 | 0.3645 | 1,217 |
| 3390-9 | 10,017 | 15 | 0.3645 | 3,651 |
| 9345-1 | 1,140 | 15 | 0.3002 | 432.28 |
| 9345-2 | 2,156 | 15 | 0.3002 | 647.23 |
Table 43. Directory Storage Capacities of IBM FB-512 DASDs
| DASD Type | Megabytes for Each Volume | 512-Byte Blocks for Each Volume |
|---|---|---|
| 3370-1 | 272.4 | 558,000 |
| 3370-2 | 348.8 | 712,752 |
| 9332-400 | 175.7 | 360,036 |
| 9332-600 | 270.8 | 554,800 |
| 9335 | 392.9 | 804,714 |
| 9336-010 | 449.1 | 920,115 |
| 9336-020 | 816.8 | 1,672,881 |
| 9336-025 | 816.8 | 1,672,881 |
| 0671 | 280.5 | 574,560 |
These capacity charts are referenced in later calculations for determining data set allocations of the directory, log, and dbextent minidisks.
Table 44 shows the minimum space allocations for a log or dbextent
minidisk.
Table 44. Minimum Space Allocations for Log and Dbextent Minidisks
| DASD Type | Minimum Space Allocation |
|---|---|
| 3375 | 1 cylinder |
| 3380 | 1 cylinder |
| 3390 | 1 cylinder |
| 9345 | 1 cylinder |
| FBA | 528 Blocks |
This section shows an example of how to determine approximately equal minidisk sizes on different devices. The example uses the numbers shown in Table 39. Depending on the block size of the minidisk you are moving to, use the 512-byte column, or the 4096-byte column.
The example assumes these things:
The directory minidisk uses 512-byte blocks.
To determine how many cylinders you need on the new device, you must first find out how many blocks you have for each volume on your current device and the new device. Then, you use these numbers to find out how many cylinders you will need on the new device. To do this, you solve the equation in Determining the Number of Blocks or Cylinders on Your Current Device.
If you are moving from an FB-512 device to a count-key-data device, you already know how many blocks you have on your current device. You only have to solve the new device side of the equation in Determining the Number of Blocks or Cylinders on Your Current Device to find out how many cylinders you need on the new device. (If you use 4 096-byte blocks, divide the number of blocks on your FB-512 device by 8 before you do the equation.)
If you are moving from a count-key-data device to an FB-512 device, you only need to know how many blocks you will need on the new device. You only have to solve the current device side of the equation in Determining the Number of Blocks or Cylinders on Your Current Device to find out how many blocks you need on the new device. (If you use 4 096-byte blocks, multiply the number you solve for in the equation by 8 to find out how many blocks you need on the FB-512.)
The example uses this equation:
a * b x * d
c = e
In the equation, you solve for x to find the number of blocks or cylinders required on your new device. The other letters are variables, which are determined by the values in Table 39. The letters stand for the following attributes:
With 7 cylinders on a 3375, and a block size of 512 bytes to be moved to 3380, you would use the 512-byte column of Table 39, giving:
7 * 456462 x * 605531
959 = 885
By following these steps, you can solve for x:
1. 7 * 456462 * 885
x = 959 * 605531
2. x = approx. 4.87
To ensure that you allow enough space on the new device, increase x by 5% and round up to the next whole number. In this example, you would need 6 cylinders on the new device type.