Using multiple control paths, Using multiple control paths for path failover, Using – Dell TL2000 User Manual

Page 42: Multiple, Logical, Libraries, Library, Sharing, Control, Paths

background image

Using

Multiple

Logical

Libraries

for

Library

Sharing

Multiple

logical

libraries

are

an

effective

way

for

the

library

to

simultaneously

back

up

and

restore

data

from

heterogeneous

applications.

For

example,

the

library

can

be

partitioned

so

that

it

processes:

v

Commands

from

Application

A

(about

Department

X)

in

Logical

Library

1

v

Commands

from

Application

B

(about

Department

Y)

in

Logical

Library

2

In

this

configuration,

the

storage

slots

and

drives

in

each

logical

library

are

dedicated

to

that

library

and

are

not

shared

among

other

libraries.

Commands

issued

by

the

applications

travel

to

the

library

through

two

unique

control

paths.

Thus,

the

data

processing

for:

v

Department

X

is

confined

to

the

storage

slots

and

drives

in

Logical

Library

1

v

Department

Y

is

confined

to

the

storage

slots

and

drives

in

Logical

Library

2

Using

Multiple

Control

Paths

In

addition

to

creating

multiple

logical

libraries,

any

logical

library

can

be

configured

to

have

more

than

one

control

path.

When

configuring

additional

control

paths,

additional

library

sharing

configurations

and

availability

options

are

made

possible.

Access

to

the

logical

library

is

on

a

first-come,

first-served

basis

and

each

control

path

for

a

logical

library

can

accept

commands

while

the

library

is

in

use

by

another

control

path.

By

default,

only

the

first

drive

in

a

logical

library

will

be

LUN-1

enabled.

For

a

particular

logical

library,

you

can

enable

as

many

control

paths

as

there

are

drives

in

that

logical

library.

Using

Multiple

Control

Paths

for

Path

Failover

Command

failures

and

timeouts

are

costly.

You

want

your

library

to

run

smoothly

and

efficiently.

To

ensure

continued

processing,

the

library

offers

an

optional

path

failover

feature

that

enables

the

host

device

driver

to

resend

the

command

to

an

alternate

control

path

for

the

same

logical

library.

With

control

path

failover

installed,

the

alternate

control

path

can

include

another

HBA,

SAN,

or

library

control

path

drive.

The

device

driver

initiates

error

recovery

and

continues

the

operation

on

the

alternate

control

path

without

interrupting

the

application.

The

2U

library

does

not

support

Control

Path

Failover

and

Data

Path

Failover.

As

a

result,

there

should

be

no

license

key

entry

for

″Path

Failover

″

on

the

2U

library.

Path

Failover

is

a

combination

of

two

previous

features:

Control

Path

Failover

(key

entered

at

the

library

user

interface)

and

Data

Path

Failover

(key

entered

at

the

device

driver

interface).

The

Path

Failover

feature

is

available

for

select

LTO

4

tape

drives.

Path

Failover

is

not

supported

for

half

height

drives.

The

Path

Failover

feature

can

be

installed

by

the

customer.

For

more

information

about

using

the

path

failover

feature,

see

the

Dell

PowerVault

TL4000

Failover

Configuration

Guide,

included

with

the

library

documentation

if

purchased

at

point

of

sale

and

with

the

customer

kit

if

purchased

later.

3-2

Dell

PowerVault

TL2000

Tape

Library

and

TL4000

Tape

Library

User's

Guide