Provided by: blkreplay_1.0-3build1_amd64
blkreplay - block device testing and benchmarking tool
blkreplay [options] device
blkreplay is a utility driving the block layer of the operating system while measuring latency and throughput of I/O operations for later visualisation. blkreplay can create artificial loads (random read-write sweeps, various kinds of overload tests) or replay natural loads which have been recorded by blktrace or a similar utility run at production servers. blkreplay can be used to test physical hardware, to compare different brands of hard disks or RAID controllers, to evaluate the effect of SSD caching, to compare different block level transports like iSCSI vs Fibrechannel and so on. blkreplay parses the load data from stdin. To create load data from blktrace output, use conv_blktrace_to_load.sh script.
Influence replay duration: --replay-start=val start offset (in seconds, 0=from_start) --replay-end=val end offset (in seconds, 0=unlimited) --replay-duration=val alternatively specify the end offset as delta --replay-out=val start offset, used for output (in seconds) --start-grace=val start after grace period for filling the pipes (in seconds) Handling of conflicting I/O requests: --with-conflicts conflicting writes are ALLOWED (damaged I/O) --with-drop conflicting writes are simply dropped --with-partial partial ordering by pushing back conflicts (default) --with-ordering enforce total order in case of conflicts --strong=val mode between 0 and 2, see docs (default=1) Replay parameters: --threads=val parallelism (default=1024) --fill-random=val fill data blocks with random bytes (%, default=0) Verification modes: --no-overhead verify is OFF (default) --with-verify verify on reads --with-final-verify additional verify pass at the end --with-paranoia re-read after each write (destroys performance) Convenience: --verbose=val increase verbosity, show additional INFO: output Expert options (DANGEROUS): --o-direct use O_DIRECT (default) --no-o-direct don't use O_DIRECT, deliver FAKE results --o-sync use O_SYNC --no-o-sync don't use O_SYNC (default) --dry-run don't actually do I/O, measure internal overhead --fake-io omit lseek() and tags, even less internal overhead --simulate-io=val delay value for I/O simulation (timespec sec.nsec) --ahead-limit=val limit pipe fillahead (realtime sec.nsec) --fan-out=val only for kernel hackers (default=4) --no-dispatcher only for kernel hackers --bottleneck=val max #requests on dispatch --speedup=val speedup / slowdown by REAL factor (default=1.0) --mmap-mode use mmap() instead of read() / write() [NYI]
blkreplay was written by Thomas Schoebel-Theuer. This manual page was created from blkreplay documentation by Andrew Shadura.
Copyright 2009-2012 Thomas Schoebel-Theuer