06-10-2011 03:58 AM
we are doing some tuning tests on our older EVA6000. As we already knew, write speed could peek max 180MB/s due 2Gbit connection between eva controllers (say design feature).
For some reason, we created raid0 vdisk and our tests are big surprise - on disk group with 28 15K 136GB drives we reached 360MB/s write (with write cache enabled) and 260MB/s (with write cache disabled). See screenshot.
Any ideas how it is possible?
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06-10-2011 10:15 PM
that 180MB/s is a single port bandwidth. If you have multipathing solution the IO will pass through all the ports, so max bandwitdh will be 180MB*4 (As EVA 6000 will have 2 ports per controller). Hope this may be the situation in your case!!!
06-12-2011 01:20 AM
360 MB/s can be reached by using two host-ports. If you're using MPIO it will distribute the load over all active and optimized paths.
06-12-2011 02:22 AM
maybe I am wrong,
but have we can reach this in 1 single 2Gb pipeline between controllers? And why other raids like r10 do not perform the same way?
I think it is not multipath related,
I'll test it on other server without mpio.
06-12-2011 08:38 PM
The "HSV 200" you are observing from Command View EVA??? or the Physical Plastic Bezil of the Controller.
Why because, there are 3 models of HSV 200 controllers.
HSV 200 - 2Gb Port speed
HSV 200-A - 4Gb port speed
HSV 200-B - 4Gb Port speed(4100/6100)
All the models will be appeared as only HSV 200 in Command view EVA!!!!
06-12-2011 11:04 PM
It is sure that if the host port speed is 4Gb, either the controller would be HSV200-A or HSV200-B.
The initial model of this EVA was only with 2GB Host port, where as the Device and Mirror port speeds are 2Gb for all models.
If the host port speed is 4Gb then there is no surpise in getting 360MB/s...
06-13-2011 01:11 AM
Btw - we can not go over 180MB/s with r10 writes. Is it becouse r10 takes more bandwith (like each write goes to 2 disks -> 2x180MB/s)?
06-13-2011 01:26 AM
The HSV200 has two loop ports to the disks. A VRAID-10 write requires twice the bandwidth, because the data goes to two disk drives.
In that case the second mirror port doesn't help, because cache mirrored data need to be replicated only once.
06-13-2011 04:25 AM