Support Start > LD_PRELOAD write limiter library

Technically advanced customers may notice this variable set if they closely examine the Unix environment under which their scripts run:

LD_PRELOAD=/usr/local/lib/tigertech_write_limiter.so

This preloaded shared library tries to ensure that scripts cannot issue disk writes or unlinks at a rate that would vastly exceed our disk write limits, which could cause an outage on your site.

It currently limits writes to 10 MBps for the first 200 MB written per process, and to 5 MBps for subsequent writes. It limits file and directory deletions to 300 per second.