Is there any chance that while writing to Gemfire data might get truncated?
GemFire would not accept a truncated message. When GemFire sends messages it includes the message length in the message header, so that the receiving side knows how much data it should get. On the other hand, GemFire doesn't know whether a Serializable object is serialized correctly.
What happens while writing in Gemfire cache, the member which is writing crashes, will that be truncated?
It may be, but GemFire will detect that, as I explained above.