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(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
Other than RAID-6 configuration: up to Max. capacity, in RAID-6 configuration: up to
capacity
Cache capacity *1
Total
volume
128TB
related to Snapshot
function
Total HDD Physical
In RAID-6 configuration: 270,001-530,000GB
capacity
Cache capacity *1
Total
volume
112TB
related to Snapshot
function
Total HDD Physical
In RAID-6 configuration: 530,001-790,000GB
capacity
Cache capacity *1
Total
volume
related to Snapshot
function
Total HDD Physical
In RAID-6 configuration: 790,001GB-Max. capacity
capacity
Cache capacity *1
Total
volume
related to Snapshot
function
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
2TB
270,000GB
4GB
8GB
-16GB
128TB
256TB
4GB
8GB
-16GB
112TB
240TB
4GB
8GB
-16GB
96TB
96TB
224TB
4GB
8GB
-16GB
80TB
80TB
208TB
Snapshot
#1
2TB
2TB
-24GB
-32GB
-40GB
384TB
512TB
640TB
-24GB
-32GB
-40GB
368TB
496TB
624TB
-24GB
-32GB
-40GB
352TB
480TB
608TB 736T0B
-24GB
-32GB
-40GB
336TB
464TB
592TB
16TB
Snapshot
Difference
#2
data
Snapshot
#2
2TB
Snapshot
2TB
-48GB
-56GB
768TB
896TB 1024TB
-48GB
-56GB
752TB
880TB 1024TB
-48GB
-56GB
864TB 1024TB
-48GB
-56GB
720TB
848TB 1024TB
3.2TB
Snapshot
Reserved
area
Difference update
#8
-128GB
-128GB
-128GB
-128GB
20
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