configuration choices with Dell CERC (adaptec 2610SA)

[user]

I am going to use a Dell CERC (adaptec 2610SA 6-port) (_not_ 21610sa
16-port) SATA raid card.

I am familiar with dell PERCs, and FreeBSD and RAID in generl, but I
wanted to go over some of the configuration choices that the adaptec BIOS
is giving me when I attempt to create a mirror:

Read caching: yes/no (default is yes)

(read caching does not rely on a battery, and is completely "safe",
right?  I am going to set this to "yes", however I wonder - why would
anyone _ever_ set it to "no" ?)

Write caching: enable/disable

(this is the one that can get you into trouble if the system loses power
before a write is committed to disk, and the battery is dead, right?  I am
going to set this to "disable" because I do not think the 2610SA has a
battery ... right ?)

Rebuild rate: high/medium/low

(I have no idea what this means - I never saw this in adaptec bios before
... can anyone define exactly what this means ?)

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Any general comments / suggestions are appreciated as well.

Thanks a lot.