NEC D8-30, Configuration Manual

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20
(Notes on using Snapshot Function)
In case you use Snapshot function (without replication) with the D8 Series, select the minimum
size of cache memory from the following table according to the total HDD capacity and the total
volume related to usable Snapshot function:
Total HDD Physical
capacity Other than RAID-6 configuration: up to Max. capacity, in RAID-6 configuration: up to
270,000GB
Cache capacity *1 4GB 8GB -16GB -24GB -32GB -40GB -48GB -56GB -128GB
Total volume
related to Snapshot
function
128TB 128TB 256TB 384TB 512TB 640TB 768TB 896TB 1024TB
Total HDD Physical
capacity In RAID-6 configuration: 270,001-530,000GB
Cache capacity *1 4GB 8GB -16GB -24GB -32GB -40GB -48GB -56GB -128GB
Total volume
related to Snapshot
function
112TB 112TB 240TB 368TB 496TB 624TB 752TB 880TB 1024TB
Total HDD Physical
capacity In RAID-6 configuration: 530,001-790,000GB
Cache capacity *1 4GB 8GB -16GB -24GB -32GB -40GB -48GB -56GB -128GB
Total volume
related to Snapshot
function
96TB 96TB 224TB 352TB 480TB 608TB 736T0B 864TB 1024TB
Total HDD Physical
capacity In RAID-6 configuration: 790,001GB-Max. capacity
Cache capacity *1 4GB 8GB -16GB -24GB -32GB -40GB -48GB -56GB -128GB
Total volume
related to Snapshot
function
80TB 80TB 208TB 336TB 464TB 592TB 720TB 848TB 1024TB
Note) The above “RV total capacity (when using RDR/DR)” is the capacity in case the buffer area of
semi-synchronous sequence is 256MB
*1 128GB is with 4 nodes configuration.
Total volume related to Snapshot function
＝
Master volume capacity
＋
Snapshot volume capacity
＋
Snapshot reserved area capacity
example)
creating 8 generation Snapshot volume for master volume of 2TB, and assuming the reserved
area capacity per generation to be 20%,
Reserved area capacity
＝
2TB x 20% x 8 = 3.2TB
Total volume related to Snapshot function
＝
2TB + 16TB + 3.2TB = 21.2TB
Master
Snapshot
#1
Snapshot
#2
Snapshot
#2
Snapshot
#8
Difference
data
2TB
2TB
2TB
2TB
2TB
16TB
Snapshot
Reserved
area
Difference update
3.2TB