Hi, On Wed, 22 Apr 2020 at 08:24, KaiKai Chen <fast.marmot@xxxxxxxxx> wrote: > > I have some basic questions: > > 1. Is following a correct understanding? > If time_based is not set and nrfiles = 1 and size = 1GB. > A sequential write job will write 1GB worth of data and create a > "solid" 1GB file (writes will cover all file blocks). Assuming no errors and the "file" doesn't have an immutable smaller size. > A random write job with norandommap = 0 will write 1GB worth of data > and create a "solid" 1GB file (writes will cover all file blocks). Same caveat as above yes (the file will actually be preallocated before I/O is done (at least on Linux)). > A random write job with norandommap = 1 will write 1GB worth of data > and create a 1GB file with potential "holes" (some file blocks may > not be written). Due to preallocation (see above) the file may not have holes in the "sparse file" sense. But yes, some areas of the file (if it didn't already exist at the right size and we're talking about a file in a filesystem etc) likely won't be written by the main job (I think they would contain zeros). > 2. Is the following a valid usage of fio's write and verify capabilities? > If so, is it possible to add "time_based" and "runtime" parameters to > the write-job and still expect verify-job to function correctly (i.e. > verify data that was written within runtime)? If you use time_based and verify then the initial writes just use up all the time and there's no time for the verify (I think fio prints a warning in that circumstance). > Also, does "verify_only=1" mean the verify-job's "rw" parameter is > ignored? (suppose we've written sequentially, but want to verify the > data through random or sequential reads) > https://fio.readthedocs.io/en/latest/fio_man.html#cmdoption-arg-verify-only > mentioned that "verify_only" flag "Do not perform specified workload, > only verify data still matches previous invocation of this workload." No but it does mean the initial "phase" of the job is skipped. If you have say rw=write verify=crc32c then the writes happen and then once the write phase is over fio switches to a verify phase. If you do rw=write verify=crc32c verfy_only=1 then the write phase is skipped and it goes straight into trying to verify the data in the file. > > [write-job] > ioengine=libaio > bs=4K > size=1GB > numjobs=2 > iodepth=64 > rw=randwrite > direct=1 > verify_state_save=1 > verify=crc32c > do_verify=0 > serialize_overlap=1 > > [verify-job] > ioengine=libaio > bs=4K > size=1GB > numjobs=2 > verify_state_load=1 > verify_only=1 > iodepth=64 > rw=randread > direct=1 > verify=crc32c > > Thanks! The above job file may not work as expected because the filenames chosen by the verify-job, er, jobs likely won't match those used for the write-job jobs - take a look at the files in the current working directory when that finishes to see what I mean. -- Sitsofe | http://sucs.org/~sits/
