These calculations overestimate the space that is used by metadata by a small amount, but the precise
details of each volume do not need to be known.
Examples:
• For an FB storage pool with 6,190 extents in which you expect to use thin provisioning and allocate up
to 12,380 extents (2:1 overprovisioning) on 100 volumes, you would have a pool overhead of 23 extents
-> (100*2+12380/10)/64=22.46.
• For a CKD storage pool with 6,190 extents in which you expect to allocate all the space on 700 volumes,
then you would have a pool overhead of 39 extents -> (700*2+6190/10)/53=38.09.
RAID capacities
Use the following information to calculate the raw capacity and usable capacity for High Performance
Flash Enclosures Gen2.
RAID 6 is the recommended and default RAID type for all drives over 1 TB. RAID 6 and RAID 10 are the
only supported RAID types for 1.92 TB Flash Tier 2 and 3.84 TB Flash Tier 1 drives. RAID 6 is the only
supported RAID type for 7.68 TB and 15.36 TB Flash Tier 2 drives.. RAID 5 is not supported for drives
larger than 1 TB, and requires a request for price quote (RPQ). For information, contact your sales
representative.
Table 21. RAID capacities for High Performance Flash Enclosures Gen2
Flash drive disk
size
Physical
capacity of
Flash drive
set
Rank type Effective capacity of one rank in number of extents
RAID-10 arrays RAID-5 arrays RAID-6 arrays
3 + 3 4 + 4 6 + P 7 + P 5 + P + Q 6 + P + Q
800 GB 12.8 TB FB Lg Ext 2133 2855 4300 5023 3578 4300
FB Sm Ext 136542 182781 275254 321475 229015 275239
CKD Lg Ext 2392 3203 4823 5633 4013 4823
CKD Sm Ext 126821 169768 255651 298601 212705 255655
1.6 TB 25.6 TB FB Lg Ext 4301 5746 n/a n/a 7191 8636
FB Sm Ext 275284 367771 n/a n/a 460243 552727
CKD Lg Ext 4824 6445 n/a n/a 8065 9686
CKD Sm Ext 255684 341586 n/a n/a 427475 513372
1.92 TB 15.4 TB FB Lg Ext 5168 6902 n/a n/a 8636 10370
FB Sm Ext 330783 441769 n/a n/a 552748 663727
CKD Lg Ext 5796 7741 n/a n/a 9686 11631
CKD Sm Ext 307231 410315 n/a n/a 513392 616474
3.2 TB 51.2 TB FB Lg Ext 8637 11527 n/a n/a 14417 17307
FB Sm Ext 552771 737753 n/a n/a 922733 1107703
CKD Lg Ext 9687 12928 n/a n/a 16170 19412
CKD Sm Ext 513414 685225 n/a n/a 857029 1028843
3.84 TB 61.4 TB FB Lg Ext 10371 13839 n/a n/a 17308 20776
FB Sm Ext 663766 885747 n/a n/a 1107725 1329703
CKD Lg Ext 11632 15522 n/a n/a 19412 23302
CKD Sm Ext 616506 822682 n/a n/a 1028848 1235028
7.68 TB 123 TB FB Lg Ext n/a n/a n/a n/a 34650 41587
FB Sm Ext n/a n/a n/a n/a 2217663 2661631
CKD Lg Ext n/a n/a n/a n/a 38863 46643
CKD Sm Ext n/a n/a n/a n/a 2059760 2472118
Chapter 4. Physical conguration 59
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