If anybody see that:
It is not quite true.
NetApp's 9000 IOPS were reached with one head (3020) and 28 disks -
the hole sysem (2 heads 112 disks reached ~ 15000 iops)
EMC's 1700 IOPS were reached with one sp and 8 disks -
the hole sysem reached ~14000 iops.
All those could be red on veritest site:
Just my correction - there is no magic here !
One should remember:
\- Equallogic is working with active/standby controllers but they can cluster 2,3,4,... systems together so that one lun will be served over all controllers
\- the other both with active/active (NetApp - 2 heads (clustered - it is possible to buy only one head - rational ?? EMC - one head with 2 SPs)
i.e. one lun can be served only per one controller but the perfomance of the hole system could be higher, when enough disks are used and both controllers are configured properly.
Please can someone clarify something for me. Based on ChristianZ comment on EqualLogic working in active/standby mode, when looking at the Storage / SAN Compatbility Guide PDF it shows in the SAN Array Model Reference table:
EqualLogic --> PS Series --> Active/Active --> Fixed
So can someone please explain the Active/Active in the table versus the Active/Standby comment in the thread. Which one is it?
I'm pretty sure the Equallogic boxes are supposed to be using in Active/Passive for ESX, well that's what the Equallogic guys told us.
On that note we've been looking at one of their boxes today, gotta say I'm impressed!
Yeah, I had a demo last week and was very impressed too. Adding arrays literally doubles, triples etc your throughput since each unit has control modules. As opposed to have a control module with multiple disk shelves all connected to your SPs.
But I would really like to get to the bottom of the correct setup for the PS series. Does this look like a documentation error in VMware guide?
Anyone got a PS series configured in production? What's your settings and path policy?
My configuration shows "fixed" althought they are working als active/standby.
I have tested the controller failover many times and it was always working w/o problems.
Maybe wohharow could correct it - when he sees that (would be nice).
For performance values check this:
ok, so only one control module is active. Would I be correct in saying that both HBAs in the ESX host would be actively serving I/O but ultimately arrive at the one active control module (which could have 1,2 or 3 network connections)?
I have 2 PS300's and they are indeed active/passive. Path policy is fixed as equallogic will handle the redirection/loadbalancing on its on end. They use trunking so the client only sees one target.
me again.... I think there is some confusion in the thread about what VMWare is describing as Act/Act. My impression is they are talking about using HBAs on the ESX host side in an Act/Act config. Since ESX shouldn't be able to tell if an array is running Act/Act or Act/Pass at the controller level. (if the array is built correctly.)
My conclusion is from knowing that I can run Multiple Qlogic 405x cards in a server all Actively working to connect to volumes on an EQLX array, while the arrays are Act/Pass on the controller side. (I have this running in my lab)
**I'll take this time to remind people not to confuse availability with uptime, if you are running Act/Act at the controller level and lose a controller then you get a 50% degridation in performance with a failure. While in an Act/Pass controller setup you not only stay online, but at 100% of performance. **
I hope that I've cleared up some of the confusion and not added to it. I'm also glad to see everyone in the thread enjoyed their demo!
-also- Thanks Femi !
EqualLogic --> PS Series --> Active/Active --> Fixed
It is my understanding that the second controller is really 'passive' - it does not present any LUNs while being passive. After failover, it takes over the IP addresses of the former active controller - otherwise you'd deal with 7 IP addesses in a single-member group, no?
An Active/Passive Fibre Channel array works different. The 'passive' controller does present the same set of LUNs, but it answers with a "NOT READY" response to I/O requests. It must present the LUNs, so that the multipath solution on the host 'knows' that there are standby paths it can failover to.
But depending on the storage used it also dictates whether the HBA cards in an ESX host are both serving I/O or just one of them.
We use ESX with an EMC fibre SAN and only one HBA is serving I/O, then if the card fails the second card will take over. It is my understanding from this thread that when using ESX with EqualLogic storage both HBAs can be configured to spread the I/O between them, and that this I/O will arrive at the single active controller.
Would someone confirm or refute my statement just I know for myself. Thanks.
I am not familiar with your EMC box - maybe this is a low-end FC array like an HP MSA where each controller has only one host port and a strict A/P controller software.
On a midrange array, where a controller has multiple host ports, they go to different fabrics. In that case, you can access different disks over different Fibre Channel adapters.
iSCSI is a special case if you use the ESX software initiator, because it currently supports only one path. On the other hand, it is my understanding that you can access different disks through different iSCSI HBAs to the same EqualLogic PS controller which has 3 active ports.
Should this controller fail, the other one will take up its identity (IP addresses). This should be mostly transparent for ESX (maybe and I/O retry) and ESX does not initiate a failover like in the FC world, because there are no standby paths here.