isutl

Verify, recover, and optimize ISAM files (Revision 4 or higher)

The ISAM file maintenance utility (isutl) performs maintenance on Revision 4 or higher ISAM files. Maintenance includes verifying the integrity of files, recovering corrupted files, reclaiming deleted record space, converting to compressed or static RFA file types, ordering data by a particular key, and packing indexes.

Isutl has the following options:

• isutl -b - Manage ISAM file buckets

• isutl -c - Clear an ISAM file

• isutl -ex - Extend freelist in an ISAM file

• isutl -f - Fast-load a sequential file

• isutl -i - Launch the information advisor

• isutl -p - Patch an ISAM file to another version

• isutl -r - Rebuild an ISAM file (Revision 4 or higher)

• isutl -s - Check and resynchronize ISAM file if out of sync (Revision 6 or higher)

• isutl -v - Verify the integrity of an ISAM file (Revision 4 or higher)

To improve performance, isutl takes advantage of of SSDs, large amounts of memory, parallel and asynchronous processing using multi-threading, and atomic (non-locking) operations. Several configurable parameters occur automatically based on the number of CPU cores available, but if you need to make adjustments based on your available hardware or circumstances (for example, limiting the amount of disk space used), you can set one or more of the following environment variables before running isutl.

We recommend you do not set these environment variables unless you are advised to do so by Synergy/DE Developer Support.

• IU_FEEDERTHREADS

• IU_IDXTHREADS

• IU_KEYTHREADS

• IU_SORTTHREADS

Isutl uses as many cores as the number of keys plus 1 (up to eight cores) and many gigabytes of memory on large files. As a result, if you have a memory or core-limited machine (for example, a Core i7 or virtual machine with eight cores and 16 GB of memory), running more than one isutl may be detrimental to the isutl performance. Running isutl on a virtual machine with fewer cores than the maximum number of keys is detrimental to the recovery of large ISAM files.

We recommend that you at least try to use an SSD for the temporary work drive, if you specify one. If you do not have any SSD drives, setting IU_SORTTHREADS to a lower value (or 1) may improve performance. If you do not have enough disk space for the key files (size of index * 3), setting IU_KEYTHREADS to a lower value may reduce the temporary space required but will cause the .is1 file to be reread multiple times.