31 write operations occurring in parallel? Or, perhaps, 31 concurrent I/Os, some reads some writes? If this is the case using vxbench specifying rand_write, nthreads=5, for example, should result in concurrency=5 during the run of the vxbench utility.
I am skeptical that this will actually occur. I look in my examples and concurrency and the number of I/O threads do not match. On Tue, Sep 21, 2010 at 6:25 PM, Carl Ma <zhu_ju...@yahoo.ca> wrote: > Symantec support is very helpful on this matter. He confirmed that > concurrency is the number of I/O operation on the volume. > > For example: > > 4275 START write vdev homevol01 block 5771246912 len 128* concurrency 31*pid > 6134 > > “Concurrency 31” means there are 31 write operations on volume – homevol01. > > Cheers, > > carl > > > On 9/20/10 11:19 PM, "William Havey" <bbha...@gmail.com> wrote: > > I've not been able to find an understandable description of "concurrency". > But, I have an example vxtrace output from a simple stripe volume with a bad > stripe size: > vxtrace -g S1dg1 -f /tmp/appiolab1.out -o dev,disk | pg > > 1 START write vdev test block 35840 len 64 concurrency 1 *pid 10931 > * > 2 START write disk c1t3d0s2 op 1 block 20224 len 16 > > 3 START write disk c1t3d1s2 op 1 block 20224 len 16 > > 4 START write disk c1t3d0s2 op 1 block 20240 len 16 > > 5 START write disk c1t3d1s2 op 1 block 20240 len 16 > > 2 END write disk c1t3d0s2 op 1 block 20224 len 16 time 0 > > 3 END write disk c1t3d1s2 op 1 block 20224 len 16 time 0 > > 4 END write disk c1t3d0s2 op 1 block 20240 len 16 time 1 > > 5 END write disk c1t3d1s2 op 1 block 20240 len 16 time 1 > > 1 END write vdev test op 1 block 35840 len 64 time 1 > > All the "op 1" statements define a complete I/O, which includes 4 separate > I/Os but the concurrency is 1. By your statement the concurrency should be > 4. > > I do have this statement I found somewhere: Concurrency means "the number > of threads monitoring the i/o". But like I say, that statement is > meaningless to me. > > Sorry I can be of only a negative sort of help on this. > > On Mon, Sep 20, 2010 at 8:05 PM, Carl Ma <zhu_ju...@yahoo.ca> wrote: > > Thanks, this is important. My understanding of concurrency means this I/O > operation was split into 31 sub-tasks and are running at the same time? > > > On 9/20/10 10:43 PM, "William Havey" <bbha...@gmail.com> wrote: > > "op" is short for "operation". Each line in the output of vxtrace is > prefixed with a number. This "op number" tells you which other lines forms a > complete trace of an I/O. Examine the output of vxtrace for all lines > containing "4275" and all these lines represent one I/O. > > On Mon, Sep 20, 2010 at 6:20 PM, Carl E. Ma <zhu_ju...@yahoo.ca> wrote: > > Hi, > > We are using volume manager 5.0 on solaris 9. I have difficulty to > interpret vxtrace output. What does "op" and "concurrency" stand for? > > ==example of output line=== > 4275 START write vdev homevol01 block 5771246912 len 128 concurrency 31 pid > 6134 > 4254 END write vdev homevol01 op 4254 block 208575678 len 16 time 0 > ==end of example=== > > Doug has a script using field $9 and $11 to determine whether this is a > random or sequential operation. Is it still valid in latest vxvm? > > Thanks in advance, > > carl > > > _______________________________________________ > Veritas-vx maillist - Veritas-vx@mailman.eng.auburn.edu > http://mailman.eng.auburn.edu/mailman/listinfo/veritas-vx > > > ------------------------------ > _______________________________________________ > Veritas-vx maillist - Veritas-vx@mailman.eng.auburn.edu > http://mailman.eng.auburn.edu/mailman/listinfo/veritas-vx > > > > > >
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