nfslogd & ndbm design limitations



Introduction:
nfslogd is a daemon which runs at NFS server to log all the NFS activities from the clients. The subset of these activities is to store information about the files/links/directories. nfslogd does not use flat files to log these activities as the searching of data will become very inefficient. Instead nfslogd uses Solaris native database ndbm to log all these records. This makes searching/deleting/inserting the records very efficient. nfslogd stores two set of records for each file/link/directory. These records are primary & secondary. The write-up is aimed at exposing ndbm design limitations. These limitations are finally exposed to the user of ndbm i.e., nfslogd. As a result of this limitation, nfslogd restricts limited number of files/links to be created in a directory before it starts throwing dbm error. The write-up highlights following issues -
- nfslogd key & records
- nfslogd interfacing with ndbm database
- ndbm data-structure & interfaces
- ndbm database data organisation
- ndbm design insert/fetch/delete design
- positioning new record in the database & split mechnism
- limitations of the database and hence nfslogd
Please find complete writeup with the analysis here...

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