| Q1. |
What is the difference between the HP StorageWorks XP Continuous Access Synchronous, HP StorageWorks XP Continuous Access Asynchronous, and HP Storage Works XP Continuous Access Journal products? |
| A1. |
HP StorageWorks XP Continuous Access Synchronous mirrors between arrays using a synchronous interface, where writes from the host to the primary data copy are not acknowledged as complete until the secondary data copy has also acknowledged the write as complete. HP StorageWorks XP Continuous Access Asynchronous and HP StorageWorks XP Continuous Access Journal use an asynchronous interface, where writes from the host to the primary data copy are acknowledged as complete as soon as the write occurs to the primary copy. Then writes to the secondary copy are completed in the background. |
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| Q2. |
What is the difference between HP StorageWorks XP Continuous Access Asynchronous and HP StorageWorks XP Continuous Access Journal? |
| A2. |
HP StorageWorks XP Continuous Access Asynchronous manages writes to the secondary data copy in a cache-based side-file, while HP StorageWorks XP Continuous Access Journal manages writes to the secondary data copy in a disk-based journal file. When these writes are completed to the secondary data copy, the write in either the side-file or journal are removed from these respective files.
In addition with HP StorageWorks XP Continuous Access Asynchronous, the primary array pushes the data to the secondary array, while with HP StorageWorks XP Continuous Access Journal, the secondary array pulls the data from the primary array. Thus HP StorageWorks XP Continuous Access Journal reduces the workload on the primary array. |
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| Q3. |
Why would I choose one kind of remote replication over the other? |
| A3. |
HP StorageWorks XP Continuous Access Synchronous Software provides the absolute highest level of concurrency, but can possibly have performance impact on the host application. HP StorageWorks XP Continuous Access Asynchronous Software and HP StorageWorks XP Continuous Access Journal Software have no performance impact on the host application. HP StorageWorks XP Continuous Access Asynchronous is a better choice if the link to the secondary site is highly available. HP StorageWorks XP Continuous Access Journal is a better choice if the link to the secondary site is not necessarily highly available, or is subject to bandwidth contention from other applications. |
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| Q4. |
How are these products licensed? |
| A4. |
HP StorageWorks XP Continuous Access Software is licensed on the total used capacity of all source and copy volumes on the disk array. |
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| Q5. |
What remote link technologies are supported? |
| A5. |
HP StorageWorks XP Continuous Access Software supports a wide range of remote link technologies, including Fibre Channel, DWDM, and high performance converters for ATM, SONET/SDH, and IP. |
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| Q6. |
What clustering software is supported by HP StorageWorks XP Continuous Access Software? |
| A6. |
Supported clustering software includes HP Metrocluster with XP Continuous Access and HP Continentaclusters (HP-UX), HP StorageWorks XP Cluster Extension for Windows, HP StorageWorks XP Cluster Extension for Linux, HP StorageWorks XP Cluster Extension for Solaris, and HP StorageWorks XP Cluster Extension for AIX. |
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