IBM Tivoli Storage Manager for UNIX and Linux Backup-Archive ...

Manager client detects sparse files during a backup operation and marks them assparse on the Tivoli Storage Manager server.Note: Sparse files do not apply to Mac OS X.Tivoli Storage Manager backs up a sparse file as a regular file if client compressionis off.Related reference“Compression” on page 283The compression option compresses files before you send them to the server.Compressing your files reduces data storage for backup versions and archivecopies of your files. It can, however, affect Tivoli Storage Manager throughput. Afast processor on a slow network connection benefits from compression, but a slowprocessor on a fast network connection does not.“Makesparsefile” on page 344Use the makesparsefile option with the restore or retrieve commands to specifyhow sparse files are recreated.NFS hard and soft mountsWhen Tivoli Storage Manager connects a backup-archive client to an NFS filesystem, you can use either a hard mount or a soft mount. Tivoli Storage Manageruses the nfstimeout option setting to determine how long to wait for an NFSsystem call to respond before timing out; this applies to hard and soft mounts. Thedefault is 0 seconds. This means that Tivoli Storage Manager uses the defaultbehavior of NFS system calls.You should be aware of the consequences of hard and soft mounts if the mountbecomes stale (for example, if the server for the file system is not available).Hard mount— If the NFS file system is hard mounted, the NFS daemons will tryrepeatedly to contact the server. The NFS daemon retries will not time out,will affect system performance, and you cannot interrupt them, but controlwill return to Tivoli Storage Manager when the nfstimeout value isreached.Soft mount— If the NFS file system is soft mounted, NFS will try repeatedly tocontact the server until either:v A connection is establishedv The NFS retry threshold is metv The nfstimeout value is reachedWhen one of these events occurs, control returns to the calling program.Note: On Solaris and HP-UX, the nfstimeout option can fail if the NFSmount is hard. If a hang occurs, deactivate the nfstimeout option andmount the NFS file system soft mounted, as follows:mount -o soft,timeo=5,retry=5 machine:/filesystem /mountpointThe parameters are defined as follows:soft Generates a soft mount of the NFS file system. If an error occurs,the stat() function returns with an error. If the option hard is used,stat() does not return until the file system is available.164 IBM Tivoli Storage Manager for UNIX and Linux Backup-Archive Clients Version 6.1: Installation and User’s Guide