| General |
| Q1. |
What is the primary problem solved by Advanced Data Guarding? |
| A1. |
As storage capacities continue to rapidly expand, customers need greater level of disk drive fault protection, which can be implemented without doubling the investment in disk drives or a new storage infrastructure. Currently, RAID 5 is only recommended to protect up to 14 disk drives in an array. RAID 1 provides greater fault protection, but requires every drive to be mirrored and is too costly for most customers to implement on large RAID volumes. Customers want the protection of RAID 1 or better with an implementation cost
similar to RAID 5. |
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| Q2. |
How is this problem addressed with Advanced Data Guarding? |
| A2. |
With Advanced Data Guarding (RAID ADG), customer can safely and economically protect a RAID volume up to 2 TB and a total of 56 disk drives. RAID ADG offers fault protection greater that RAID 1 or RAID 5 and only consumes the capacity of 2 disk drives for distributed parity data. |
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| Q3. |
How can Advanced Data Guarding be obtained for the Smart Array 5300 Controller? |
| A3. |
- For customers of Smart Array 5304/128 Controller, Advanced Data Guarding is a standard feature and is included when purchased. Customers purchasing a SA-5304/128 prior to this feature becoming available can receive the latest firmware version to activate this functionality.
- For customers of Smart Array 5302/64, Advanced Data Guarding is an upgrade and can be purchased through HP's normal channels and through HP's Small and Medium Business Online Store (Part Number 199371-B21).
- For customers of Smart Array 5302/32 Controller, customers must also upgrade the cache to 128 MB (Part Number 153506-B21) for Advanced Data Guarding to be supported. Both the 128 MB Cache module and Advanced Data Guarding are available through HP's normal channels and through our Internet store.
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| Q4. |
Is Advanced Data Guarding available with all Smart Array 5300 controllers? |
| A4. |
No. Advanced Data Guarding is only supported on controllers with 64 MB of controller cache or greater. The SA5302/32 only has 32 MB of cache and will not support this feature unless the controller cache is upgraded. Once the cache memory in increased it can also be upgraded to include Advanced Data Guarding. ADG is offered as a standard feature to the SA5304/128 and is an upgrade feature for all other models. |
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| Q5. |
What does the abbreviation RAID ADG mean? |
| A5. |
ADG is an abbreviation for Advanced Data Guarding - the formal name for this level of RAID. |
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| Q6. |
What is RAID ADG? |
| A6. |
RAID ADG is essentially an extension of RAID level 5, which allows for additional fault tolerance by using a second independent distributed parity scheme. Data is striped across a set of drives, just like in RAID 5, and a second set of parity is calculated and written across all the drives. RAID ADG provides for an extremely high data fault tolerance and can sustain multiple simultaneous drive failures. This is a perfect solution when data is mission critical. |
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| Q7. |
When should customers use RAID ADG? |
| A7. |
- When a higher level of fault protection than RAID 5 is required and high capacity utilization is desired.
- When a higher level of capacity utilization than RAID 1 or RAID 0+1 is required and maintaining a higher level of fault protection is desired.
- When customers require a large RAID volume incorporating between 10 and up to 56 disk drives.
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| Q8. |
What is the difference between RAID ADG and RAID 1? |
| A8. |
RAID ADG offers a lower implementation cost and higher capacity utilization for 5 drives or more. RAID ADG requires the capacity of two drives for fault tolerance for any size disk array. In addition, RAID ADG provides a higher level of fault tolerance due to the probability of RAID 1 suffering a second drive failure in the same mirror set as the first drive failure is higher than a third drive failure in a RAID ADG set. RAID 1 provides the highest possible RAID performance. |
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| Q9. |
What is the difference between RAID ADG and RAID 5? |
| A9. |
RAID ADG provides a much higher level of fault tolerance than RAID 5. RAID ADG allows two simultaneous drive failures without down time or data loss. RAID 5 only allows 1 drive failure. Due to this added protection, users can set up larger RAID volumes spanning up to 56 disk drives. RAID 5 is recommended to protect up to only 14 drives per volume. RAID ADG has equal performance to RAID 5 when reading data but is slower when writing data due to the extra parity data that RAID ADG writes. Exact performance difference between RAID ADG and RAID 5 will vary because performance is dependent upon a number of factors. |
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| Q10. |
On which models of Smart Array is RAID ADG be available? |
| A10. |
RAID ADG is available on the SA-6404, SA-6402, and SA-5304. RAID ADG is also be available as an option for all SA-5302models. RAID ADG requires a minimum of 64MB cache. |
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| Q11. |
Does RAID ADG support Online Spares? |
| A11. |
Yes. Customers can incorporate Online Spares with RAID ADG for added data protection. |
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| Q12. |
How is RAID ADG activated? |
| A12. |
On the Smart Array 5300, RAID ADG is activated through either a software or hardware key referred to as Advanced Data Guarding Activation Module (ADAM). The SA5304 will be configured with this module in place and it can be added to the other SA5300 controller models as an option. An option kit which provides a software key to enable ADG is also available. If the ADAM Module is missing or the software key is not installed, the RAID ADG configuration option is disabled.
RAID ADG is automatically enabled as an option on the SA-6400 series, no additional hardware or software is required. |
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