Hp XP Continuous Access Software Manuel d'utilisateur télécharger pdf (Page 74)

Figure 28 Res

toring Business Copy XP P-VOLs, step 9

Combining Continuous Access XP Journal with Continuous Access XP (3DC

cascading conﬁguration)

ThelocalarrayallowsContinuousAccessXPJournal and Continuous Access XP Synchronous to

be combined. This combination is intended to ensure that the response time against host I/Os is

comparable, regardless of whether the distance between the primary and secondary sites is short or

long. This combination is also intended to ensure that the secondary site stores data that has been stored

in the primary site even if a failure occurs in the primary site. These intentions are fulﬁlled if remote copy

operations are performed using cascading connections and a three data center (3DC) conﬁguration. In a

3DC conﬁguration, an intermediate site is located between the primary and secondary sites.

Figure 29 shows an example of a 3DC cascading conﬁguration in which Continuous Access XP Journal

and Continuous Access XP Synchronous are combined. In this conﬁguration, the volume in the primary

site is a Continuous Access XP Synchronous primary volume (P-VOL). The corresponding Continuous

Access XP secondary volume (S-VOL) is the volume in the intermediate site, which is a short distance from

theprimarysite.ThisContinuousAccessXPSynchronoussecondaryvolumeisalsousedasaContinuous

Access XP Journal primary data volume. The corresponding Continuous Access XP Journal secondary

data volume is the volume in the secondary site, which is a long distance from the intermediate site. If a

host issues an I/O to the Continuous Access XP Synchronous primary volume in the primary site, data is

transferred using Continuous Access XP Synchronous and Continuous Access XP Journal to the secondary

site and is restored to the secondary data volume.

Figure 29 3DC cascading conﬁguration (combining CA XP Jour. with CA XP Sync.)

Data that Continuous Access XP Synchronous copies is stored in the Continuous Access XP Journal

primary data volume. If a failure occurs at the Continuous Access XP Synchronous P-VOL, you can

continue your business tasks using data in the Continuous Access XP Journal secondary data volume,

which contains data in the Continuous Access XP Synchronous P-VOL. Data in the Continuous Access XP

Synchronous P-VOL is restored through Continuous Access XP Journal to the secondary data volume in

the secondary site, with update sequence integrity ensured. If a failure occurs at both the Continuous

Access XP Synchronous P-VOL and S-VOL due to a disaster or any other reason, you can perform disaster

recovery using the Continuous Access XP Journal secondary data volume.

NOTE:

You must create a Continuous Access XP Synchronous P-VOL in a local array. The Continuous Access XP

Synchronous P-VOL's fence level must be Data.

Continuous Access XP Journal operations requirements and restrictions

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Hp XP Continuous Access Software Manuel d'utilisateur Page 74