The following table compares the copying operations of IBM® FlashCopy® and Hitachi Compatible FlashCopy®.
|
Feature |
IBM® FlashCopy® |
Hitachi Compatible FlashCopy® |
|---|---|---|
|
Read access to the area not specified as the copy range in the copy target during the background copying process in NOCOPY mode |
The data on the tracks subject to read operation are not copied from the copy source to the copy target. |
Sometimes the data on the tracks subject to read operation are copied from the copy source to the copy target, and other times the data are not copied to the target. |
|
Status of the relationships when on-demand copy is processed |
Relationships are withdrawn automatically when all of the copy operations processed by on-demand copy are completed. |
Relationships are maintained even when all of the copy operations processed by on-demand copy are completed. |
|
Creating TCz pairs in COPY mode or resynchronizing TCz pairs when a Compatible FlashCopy® relationship is established with the FREEZE option, and the source volume in the ELB state is specified as the S-VOL. |
PPRC pair operation completes instantly, and the pair status changes to Pending. However, until the ELB state set for the PPRC S-VOL is released, initial copy will not start. Initial copy starts when the ELB state is released, and the pair status changes to Duplex when initial copy completes. Note that if the ELB state is not released in 45 seconds, the PPRC pair will be suspended. |
TCz pair operation is rejected. |
|
Establishing a new Compatible FlashCopy® relationship by using a source volume in the ELB state when a Compatible FlashCopy® relationship is established with the FREEZE option |
A Compatible FlashCopy® relationship is established without waiting for the release of the ELB state set for the source volume. |
A Compatible FlashCopy® relationship is established when the ELB state set for the source volume is released. |
|
Reverse Restore |
After all of the copy operations processed by on-demand copy are completed, the Reverse Restore operation can be performed on the relationship created by the Incremental FlashCopy® function with NOCOPY specified or on the relationship after Restore or Reverse Restore is performed. |
After all of the copy operations processed by on-demand copy are completed, the Reverse Restore operation cannot be performed on the relationship created by the Incremental FlashCopy® function with NOCOPY specified or on the relationship after Restore or Reverse Restore is performed. |
|
Fast Reverse Restore |
Regardless of whether or not the option of the Incremental FlashCopy® function is specified, if you perform the Fast Reverse Restore, the part of the data which is copied from the S-VOL to the T-VOL will be copied from the T-VOL to the S-VOL. |
When you perform the Fast Reverse Restore specifying the option of the Incremental FlashCopy® function, only the data that has been changed on the S-VOL or the T-VOL will be copied from the T-VOL to the S-VOL. When you perform the Fast Reverse Restore function without specifying the Incremental FlashCopy® function, only the copied data from the S-VOL to the T-VOL will be copied before the Fast Reverse Restore is executed. |
|
Establishing relationships with NOCOPY specified without an option of the Incremental FlashCopy® function, then performing Fast Reverse Restore with NOCOPY specified without an option of the Incremental FlashCopy® function and I/Os. |
The relationship is released. |
The relationship is maintained with the source volume and the target volume reversed. |
|
Copying in NOCOPY mode in FlashCopy® to PPRC Primary Volume function |
When a FlashCopy® relationship in NOCOPY mode is created using a PPRC P-VOL, the data is not copied from FlashCopy® S-VOL to FlashCopy® T-VOL, and the FlashCopy® S-VOL data is copied to the PPRC S-VOL. When the FlashCopy® relationship is deleted, the PPRC P-VOL data is copied to the PPRC S-VOL data. |
When a Compatible FlashCopy® V2 relationship in NOCOPY mode is created using a TCz P-VOL, the copy operation is executed to the Compatible FlashCopy® relationship T-VOL and TCz pair S-VOL. The copy operation is not executed even if the Compatible FlashCopy® relationship is deleted. The value of BCE or BCP displays as F(FALSE) though the value of "#TRACKS YET TO BE COPIED" displayed by the ICKDSF FLASHCPY QUERY RELATIONS command changes, depending on the number of tracks in which the copy has not been completed. |
|
Copying in NOCOPY mode in the FlashCopy® to URz Primary Volume function |
- |
When Compatible FlashCopy® relationship in NOCOPY mode is created using URz P-VOL, the copy operation is executed to the Compatible FlashCopy® relationship T-VOL and URz pair S-VOL. The copy operation is not executed even if the Compatible FlashCopy® relationship is deleted. The value of BCE or BCP displays as F(FALSE) though the value of "#TRACKS YET TO BE COPIED" displayed by the ICKDSF FLASHCPY QUERY RELATIONS command changes, depending on the number of tracks on which the copy has not been completed. |
|
Receiving Failover/Failback command to TCz pairs in FlashCopy® to PPRC Primary Volume function |
Receives Failover/Failback command. |
Failover command is received, but after that, the Compatible FlashCopy® relationship T-VOL will be used as the TCz pair S-VOL. Therefore, the Failback command is rejected. |
|
Executing ReverseResync command on URz pairs in the FlashCopy® to URz Primary Volume function |
- |
The ReverseResync command is rejected because the Compatible FlashCopy® relationship T-VOL will be used as URz pair S-VOL. |
|
Execute ICKDSF command for Compatible FlashCopy® to TCz P-VOL in Pending status |
Ends Normally. |
Ends abnormally with CC=12. |
|
Establishing a TCz pair in NOCOPY mode whose P-VOL is a Compatible FlashCopy® relationship T-VOL that you establish in NOCOPY mode |
Neither FlashCopy® data nor PPRC data can be copied. |
Data can be copied from the Compatible FlashCopy® relationship S-VOL to T-VOL but not to the TCz S-VOL. In this state, if you release the Compatible FlashCopy® relationship, the data of TCz P-VOL and S-VOL will be different. |
|
Establishing a URz pair in NOCOPY mode whose P-VOL is a Compatible FlashCopy® V2 relationship T-VOL that you establish in NOCOPY mode |
- |
Data can be copied from the Compatible FlashCopy® relationship S-VOL to the T-VOL but not to the URz S-VOL. In this state, if you release the Compatible FlashCopy® relationship, the data of URz P-VOL and the S-VOL will be different. |
|
The operation with the Remote FlashCopy® function used when a TCz pair is in the Pending status. |
The relationship can be established. |
The relationship cannot be established. |
|
The operation used when relationship-creation fails in the secondary site for Preserve Mirror FlashCopy® |
The relationship on the secondary site is not created, though the local relationship might be created. In this case, the TCz volume associated with the Compatible FlashCopy® V2 relationship T-VOL is in suspend status. |
Neither local or remote relationships are created. |