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35759
December 1st, 2014 11:00
EqualLogic PS 4100 Series + VMware SIOC
Hello,
What's the recommended storage configuration in VMware for an EQL PS 4100 series array from a datastore prospective? Put another way, is there any sense in creating multiple datastores and enabling SIOC in an attempt to increase storage performance since all datastores live on the same spindles?
I'm trying to prioritize tier 1 virtual machines storage resource allocation using VMware SIOC. I currently have SIOC enabled on all datastores using the default settings (30ms). SIOC, by design, will throttle individual virtual machine storage queue slots when the datastore is congested but what if a tier 1 VM is on datastore1 and a tier 3 VM is on datastore2 and the tier 3 VM is hitting the array with an immense amount of IO causing the tier 1 VM to experience high latency? Correct me if I'm wrong but SIOC won't be able to improve performance of the tier 1 VM in this situation because it's on a different datastore than the tier 3 VM, yes?
I'm thinking about placing all VMs on a single datastore so that SIOC can do it's job. At the end of the day how will this affect performance? I understand storage arrays have individual LUN queues so how does that play out with the PS 4100? I guess what I'm asking is how do I manage virtual machine storage IO priority using a PS 4100 and VMware as efficiently as possible? 1 datastore? many datastores?
Thanks,
Steve
stevenca
13 Posts
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December 3rd, 2014 05:00
Don,
Thanks for the reply.
Technical Report (TR1066) talks about PS Series Arrays and VMware SIOC but it doesn't make a recommendation either way...
Technical Report (TR1091) states that "Because of the various load balancers in the Dell EqualLogic PS Series SAN, the Storage I/O Control (SIOC) feature should also be disabled on EQL based data stores. VMware vCenter might get false information and attempt to load balance at the same time causing unnecessary data movement."
My issue with TR1091 is that in my situation I'm not using SIOC to load balance from a capacity standpoint, I'm using it to prioritize IOPS for tier 1 VMs.
The link that you posted doesn't work, can you re-post it please?
Steve
stevenca
13 Posts
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December 3rd, 2014 06:00
Don,
I can assure you that all best practices have been implemented.
So if SIOC is disabled, how would one prevent a single VM from consuming all of the available storage I/O resources available on a PS 4100?
Thanks.
Steve
stevenca
13 Posts
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December 3rd, 2014 08:00
Don,
After DelayedACK was configured, all hosts were reconnected to storage (i.e. all hosts were rebooted).
We are utilizing vStorage APIs (including VAAI) whenever we can.
So what you're saying is that utilizing array offload technologies (e.g. VAAI) and other array access techniques that bypass the ESXi kernel/storage stack (e.g. in-guest iSCSI) can trigger SIOC because of the additional latency created that ESXi doesn't take into account?
That makes sense but I'm still bothered by the fact that we don't have an easy way to control individual VM storage I/O access as a whole (unless of course I only enable the SIOC IOP limit feature and hard code these limits on a per VM basis).
Steve
stevenca
13 Posts
0
December 3rd, 2014 09:00
Don,
Will do.
Thanks for the information.
Steve