have you tried the micro sd card??i dont trust anymore external usb flash drivers for user manager. disk is missing from system/disks or changing name from disk1 to disk4 without reason. and nobody can login after that because user manager database cannot be found.
internal flash is small 128mb but user manager is working flawless until flash is full.. i dont know why but sqldb file is increasing every day even without adding any users. yesterday it was 266kb and today is 396kb.
i dont use logs. logsdb is always 6kb.
i wish i had bought rb1100ah4 dude edition with ssd for user manager but it was not available at that date i bought ccr1009.