IBM DS6000 Series manual Placement of data, Virtualization hierarchy

Array	RAID
Sites	Array
	Data
	Data
	Data
	Data
	Data
	Data
	Parity
	Spare

Rank

Type FB

1 GB FB 1 GB FB 1 GB FB

Server0

	Extent		Logical
	Pool		Volume
1 GB FB	1 GB FB	1 GB FB
1 GB FB	1 GB FB	1 GB FB

LSS

FB

Address	Volume	Host
Group	Group	Attachment

X'0x' FB

4096

addresses

LSS X'07'

X'1x' CKD

4096

addresses

Figure 4-11 Virtualization hierarchy

4.2.10 Placement of data

As explained in the previous chapters, there are several options on how to create logical volumes. You can select an extent pool that is owned by one server. There could be just one extent pool per server or you could have several. The ranks of extent pools could come from arrays on different loops or from the same loop. Figure 4-12 on page 81 shows an optimal distribution of four logical volumes within a DS6000. Of course you could have more extent pools and ranks, but when you want to distribute your data for optimal performance, you should make sure that you spread it across the two servers and across the two loops and across several ranks.

If you use some kind of a logical volume manager (like LVM on AIX) on your host, you can create a host logical volume from several DS6000 logical volumes (LUNs). You can select LUNs from different DS6000 servers and loops as shown in Figure 4-12.By striping your host logical volume across the LUNs, you will get the best performance for this LVM volume.

80DS6000 Series: Concepts and Architecture