A new Disaster Recovery site has been established using Metro Mirror to hold synchronous data at both sites. After the Metro Mirror is started， one of the most important applications， a DB2 database， slows down. An analysis shows that the I/O rate （especially write I/Os） is less than 40% compared to the former rates.  What is the best explanation for this behavior（）

• A、the bandwidth of the PPRC connection between the two sites is too small
• B、the DS8000 SFI at the remote site was shipped with slower disks
• C、I/O rates vary， depending on the distance between the two sites and the rates cannot be changed easily， due to latency
• D、the DB2 database does not work with Metro Mirror without an additional license