xl

quorum_majority_write() returns true if 11 disks are up (among 16)
quorum_majority_read() returns true if there are 6 parts (among 16) available of the highest version

In XL, during PUT/DELETE:
1) check if quorum_majority_write(), if not return error
2) on each disk, write parts (or delete) to .temp/bucket/object/
3) increment version number, insert op type (put/delete) in .temp/bucket/object/temp.json
4) if all disks are up mv .temp/bucket/object/ bucket/object/

In XL, during READ/STAT:
1) check if object available at .temp/bucket/object, if not found check bucket/object, if not found return ErrNoObject
2) if the object is at .temp/bucket/object and we have quorum_majority_read() return the read data
3) else if the object is at bucket/object and we have quorum_majority_read() return the read data