Administrator Guide

Solution Architecture
14 Dell EMC Ready Solution for HPC PixStor Storage | Document ID
operational and only a single SAS cable remains connected to each ME4084, the solution can still provide
access to all data stored in those arrays.
Figure 4 ME4084 drives assigned to LUN for Standard Configuration.
When the optional High Demand Meta Data module is used, the eight RAID 6 are assigned just like the
standard configuration and are also used only to store data. However, instead of SSDs, the last four disk slots
have NLS SAS3 HDDs to be used as hot spares for any failed disk within the array, see Figure 5.
.
Figure 5 ME4084 drives assigned to LUN for Configuration with High Demand Meta Data.
An additional pair of R740 servers are connected to one or more ME4024, which are used to store metadata.
Those arrays are populated with SAS3 SSDs that are configured as twelve RAID 1 Virtual Disks (VDs), and
disks for such VDs are selected starting in disk slot 1 and for its mirror moving twelve disks to the right (slot N
& Slot N+12), as can be seen in Figure 6. Similar to the standard configuration, when a single ME4024 array
is used, GPFS is instructed to replicate metadata using pairs of RAIDs 1 LUNs as part of a failure group.
However, if more than one ME4024 is used, then LUNs part of failure groups are kept in separate arrays.