Diskwarrior on Drobo, not enough memory

I have a Drobo, 4x2Tb, 1,3 Tb used.
I use a MacBook Pro with 4Gb RAM. Diskwarrior (v4.1.1) stops after quite a while with an error message «There is not enough memory. Restart from the Diskwarrior disc and try rebuilding again (… error code 2154)».

Does this indicate that there is something wrong with the Drobo filesystem? I use MacOSX 1.5.8. DiskUtility found no errors.

I got a yellow warning I was running out of space toward the end of DW. Many things repaired and all is well.