Hp ProLiant DL585 G2 Storage-Server User Manual download pdf (Page 33)

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Figure 6 Two arrays (A1, A2) and ﬁve logical drives (L1 through L5) spread over

ﬁve physical drives

NOTE:

This type of conﬁ guration may not apply to all storage servers and serves only as an example.

Through the use of basic disks, primary partitions or extended partitions can be created. Partitions

can only encompass one LU N. Through the use of dynamic disks, volumes can be created that span

multiple LUNs. The Windows Disk M anagement utility can be used to convert disks to dynamic and back

to basic, and manag e the volumes residing on dynamic disks. Other options include the ability to

delete, extend, mirror, and repair these elements.

Partitions

Partitions exist as either primary partitions or extended partitions and can be composed of only one basic

disk no larger than 2 TB. B asic d isk s can also only c ontain up to four primary par titions, or three primary

partitions and one extended partition. In addition, the partitions on them cannot be extended beyond the

limits of a single LUN. Extended partitions allow the user to create multip le logical drives. These partitions

or logical disks can be assigned d rive letters or be used as m ount points on existing disks. If mount points

are used, it should be noted that Ser vices for UNIX (SFU ) does not support mount points at this time. The

use of mount points in conjunction with NFS shares is not supported.

Volumes

When planning dynamic disks and volumes, there is a limit to the amount of growth a single volume can

undergo. Volumes are limited in size and can have no more than 32 separate LUNs, with each LUN not

exceeding 2 terabytes (TB), and volumes totaling no more than 64 TB of disk space.

The RAI D level of the LUNs included in a volume must be considered. All of the units that ma ke up a

volume should have the same high-availability characteristics. In other words, the units should all be of

the same RAI D level. For example, it would not be a good practice to include both a RAID 1+0 and a

RAID 5 array in the same volume set. By keeping all the units the same, the entire volume retains the

same performance and high-availability characteristics, making m anaging and maintaining the volume

much easier. If a dynamic disk goes ofﬂine, the entire volume dependent on the one or more dynamic

disks is unavailable. There could be a potential for data loss depending on the nature of the failed LUN.

Volumes are created out of the dynamic disks, and can be expanded on the ﬂy to extend over multiple

dynamic disks if they are spanned volumes. However, after a type of volume is selected, it cannot be

altere d. For example, a spanning volume cannot be altered to a mirrored volume without deleting and

recreating the volume, unless it is a simple volume. Simple volumes can be mirrored or converted to

spanned volumes. Fault-tolerant disks cannot be extended either. Therefore, selection of the volume

type is important. The same per formance characteristics on numbers of reads and writes apply when

using fault-tolerant conﬁgurations, as is the case with controller-based RAID. These volumes c an also be

assigned drive letters or be mounted as mount points off existing drive letters.

The administrator should carefully consider how the volumes will be carved up and what groups or

applications will be using them. For example, p ut ting several stora ge-intensive applications or groups into

the same dynamic disk set would not be efﬁcient. These applications or groups would be better served

by being divided up into separate dynamic disks, which could then grow as their space requirements

increased, within the allowable growth limits.

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Hp ProLiant DL585 G2 Storage-Server User Manual Page 33

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