Implementing the IBM Storwize V7000

Chapter 13. RAS, monitoring, and troubleshooting for an IBM Storwize V7000 system 525

Expansion canister and LED status

As shown in Figure 13-2, there are two 6 Gbps SAS ports side by side on the canister. They

are numbered 1 on the left and 2 on the right. Each port connects four PHYs; each PHY is

associated with an LED. These LEDs are green and are next to the ports.

Figure 13-2 Canister status LEDs

In Table 13-5, we describe the LED statuses of the expansion canister.

Table 13-5 Expansion canister LEDs statuses

13.1.2 Disk subsystem

The IBM Storwize V7000 system is made up of enclosures. There are two types of

enclosures: a 2U12 that takes 12 3.5-inch drives, and a 2U24 that takes 24 2.5-inch drives.

The drives fit into the front of the enclosure, and the rear of the enclosures are identical and

have slots for two canisters and two power supplies. Enclosures are used as either control

enclosures or expansion enclosures. They are differentiated by the type of canister and

power supply they contain.

Position Color Name State Meaning

Top Green Status On The canister

is active.

Flashing The canister

has a vpd error.

Off The canister is

not active.

Bottom Amber Fault On The canister

hardware

is faulty.

Flashing The canister is

being identified.

Off No fault canister

is being

identified.

526 Implementing the IBM Storwize V7000 V6.3

An array is a type of MDisk made up of disk drives that are in the enclosures. These drives

are referred to as

members of the array. Each array has a RAID level. RAID levels provide

different degrees of redundancy and performance, and have different restrictions on the

number of members in the array. An IBM Storwize V7000 system supports hot spare drives.

When an array member drive fails, the system automatically replaces the failed member with

a hot spare drive and rebuilds the array to restore its redundancy. Candidate and spare drives

can be manually exchanged with array members.

Each array has a set of goals that describe the wanted location and performance of each

array member. A sequence of drive failures and hot spare takeovers can leave an array

unbalanced, that is, with members that do not match these goals. The system automatically

rebalances such arrays when appropriate drives are available.

An IBM Storwize V7000 system supports the RAID levels shown in Table 13-6.

Table 13-6 RAID levels supported by an IBM Storwize V7000 system

Disk scrubbing

The scrub process runs when arrays do not have any other background processes. The

process checks that the drive LBAs are readable and array parity is in synchronization. Arrays

are scrubbed independently and each array is entirely scrubbed every seven days.

Solid-state drives

Solid-date drives (SSD) are treated no differently by an IBM Storwize V7000 system than

HDDs with respect to RAID arrays or MDisks. The individual SSD drives in the storage

managed by the IBM Storwize V7000 system are combined into an array, usually in RAID 10

or RAID 5 format. It is unlikely that RAID 6 SSD arrays are used due to the double parity

impact, with two SSD logical drives used for parity only.

A LUN is created on the array, which is then presented to the IBM Storwize V7000 system as

a normal managed disk (MDisk). As is the case for HDDs, the SSD RAID array format helps

protect against individual SSD failures. Depending on your requirements, additional high

availability protection, above the RAID level, can be achieved by using volume mirroring.

RAID level Where data is striped Minimum to maximum

members

0 Data is striped on one or

more drives.

1 - 8

1 Data is mirrored between

two drives.

2

5 Data is striped across several

drives with one parity.

3 - 16

6 Data is striped across several

drives with two parities.

5 - 16

10 Data is striped across pairs of

mirrored drives.

2 - 16