On Wed, 26 Nov 2003, Rob van der Heij wrote: > On Wed, 2003-11-26 at 19:00, Alejandro Leyva Rabinovich wrote: > > > lxrtr1 is a vm with an osa dedicated, and two virtual nics, i dont > > understand why it is ALWAYS in i/o wait, but thats not the point, i dont > > VM63282 makes CP stop to consider the outstanding Read CCW for network > adapters something to wait for...
we have the ptf applied for VM63282, lxrtr1 is the only one that always is in i/o wait, it is the only user with a osa dedicated to it. > > > understand why, if the dasd 1209 are less than 30% utilized, the vm user > > goes into i/o wait state, and, i dont understand exactly what means that > > the user is in that state, also, are 9291 ioreqst a lot? > > Whether 9291 is a lot depends on what the I/O is. A single SSCH (the > unit that is being counted) may be 4 KB but could run upto 450KB. So the > 300 SSCH's could be anywhere between 1 and 135 MB/s. > > Unfortunately your RTM output does not show average connect time per I/O > (which makes me wonder about the hardware platform involved). That > number would be helpful to determine how much data is involved. the hardware is a z800 2066-0a1 and all the dasd are in a shark, zvm is 4.3 with service level 0201. > > Further, since the guest has a QDIO network device it will be classified > as I/O-wait if nothing else (see VM63282). infrac01 (the user that is working with postgres) uses a qdio device (a virtual nic), but, since we have the ptf applied it doesnt stands in q3 all the time. > > > why does, if the volume is across three dasd's (1208, 1308 and 1138), only > > 1208 receives a high rate of ioreqst? > > I believe the default for LVM is not to stripe over the volumes, so > depending on how much of the logical volume is in use you might end up > accessing data on only one of the devices. In case you *are* striping > your stripe may be large compared to the range of blocks you access in a > period of time? > when i created the logical volume i didnt specify striping, so it should be linear, thats the cause of the ioreqst > Rob > -- Alejandro Leyva Rabinovich. Jefe de la Unidad Departamental de Soporte Ticnico (Administracisn de Mainframe). Direccisn General de Informatica. Secretarma de Finanzas. Gobierno del Distrito Federal.
