Multiple DataFileDirectorie and disk failure

[mail.list.steel.mental]

HI，folks:

 

It’s seems cassandra can use multiple DataFileDirectory:

…..

  <DataFileDirectories>

      <DataFileDirectory>C:\Data1</DataFileDirectory>

      <DataFileDirectory>C:\Data2</DataFileDirectory>

      <DataFileDirectory>C:\Data3</DataFileDirectory>

         ……

  </DataFileDirectories>

…..

 

>From code I found cassandra will create a directory for each table (keyspace), 
>now I have a node which have 12 disk, and I plan to mount each disk

onto each directory:

 

C:\Data1\key_space1

C:\Data1\key_space2

C:\Data1\key_space3

C:\Data2\key_space1

C:\Data2\key_space2

C:\Data2\key_space3

C:\Data3\key_space1

C:\Data3\key_space2

C:\Data3\key_space3

 

the questions are:

1.       How does SStables of one key-space distribute among multiple data 
directory?(what distribute policy?)

2.       What fault-tolerant policy does cassandra utilize to against disk 
failure?

3.       If one disk down, What impact does one key-space have on reading and 
writing?(does whole key-space become unavailable?)

 

Thanks very much!!

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