The le system block allocaon le collecon of bits that

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: or on revoca,on of a byte ­range token •  Then update the cached indirect blocks accordingly –  Acquires the metanode token for the file –  This first node will be the metanode •  Other nodes will get the iden,ty of this metanode 2 2/4/13 CS480 Principles of Data Management Spring 2013 CS480 Principles of Data Management Spring 2013 Metanode for File Metadata (2/2) •  Metanode relinquishes the token –  The file is no longer being accessed on the metanode and ages out of the cache on that node •  If there is request from another node a_er the token is relinquished Managing File System Metadata GPFS –  Nega,ve reply –  New node will be the metanode CS480 Principles of Data Management Spring 2013 Allocation map •  Records the alloca,on status (free or in ­use) of all disk blocks in the file system –  Block alloca,on file •  Collec,on of bits that represent availability of disk space •  e.g. Requires 32 bits per disk block –  For 32 possible subblocks per data block –  Linked lists for finding a free disk block or a subblock of a par,cular size Spring 2013 How does allocation map avoid conflict? •  Interleaving free ­space informa,on about different disks –  The alloca,on map is divided into n of separated lockable regions –  GPFS can access only 1 region at a ,me •  Minimize lock conflict •  Requires updates to the alloca,on map –  Different nodes can allocate space from different regions –  Must be synchronized between nodes CS480 Principles of Data Management CS480 Principles of Data Management Spring 2013 Allocation Manager •  One of the nodes in the cluster is responsible for maintaining free space sta,s,cs about all alloca,on regions •  Ini,alizes free space sta,s,cs by reading the alloca,on map CS480 Principles of Data Management Spring 2013 Deleting large file •  A large file can be allocated over large number of regions –  Delete mess...
View Full Document

Ask a homework question - tutors are online