关于两道备份测试题的困扰

1. A customer wants to know why their backup performance to the Avamar multinode f\grid has decreased. Initially they were seeing an ingestion rate of around 5 to 7 GB/hr/node. Recently they estimated that it has slowed to around 3 to 5 GB/hr/node.
What is a probable cause for the decrease in the average ingestion rate?
A. HFS check has not been completing successfully
B. A large number of backups have been expired, causing new stripes to be created
C. New stripes are no longer being created and steady-state has been achieved
D. Garbage collection is not running, causing stripes to fill and new stripes to be created

2. A customer wants to know why their backup performance to an EMC Avamar multi-node server has decreased. Initially they were seeing an ingest rate of approximately 5 to 7 GB/hr/node.
Recently they estimated that the ingest rate has slowed to around 3 to 5 GB/hr/node.
What is a probable cause for the decrease in the average ingest rate?
A. Garbage collection is not running causing new stripes to be created
B. HFS check has found errors and has not been completing successfully
C. A large number of backups have expired causing new, relatively empty stripes to be created
D. Stripes contain more data and steady state has been achieved

对于这两道题的选择拿不定主意(本人偏向于选择1C、2D)，稳态的定义：将新数据区块添加到Avamar服务器的速率等于或小于从服务器删除过期数据区块的速率。速率的降低是达到稳态的结果，请各位专家解惑！