A number of you have reached out about how to change some of the settings around path policies, in particular how to set the default number of iops in the Round Robin path selection policy (PSP) to 1. While many of you have written scripts to do this, when you reboot the ESXi host, the defaults of the PSP are re-applied and then you have to run the scipts again to reapply the changes. Here I will show you how to modify the defaults so that when you unclaim/reclaim the devices, or indeed reboot the host, the desired settings come…
You may remember an enhancement which we made to Storage I/O Control (SIOC) in the 5.1 vSphere release whereby SIOC can now automatically determine the characteristics and thus the latency threshold of a datastore. Prior to this change, SIOC used either a default value or had customers manually set it. Neither of these were ideal, so we introduced this automatic method. However, there was little detail on how often this latency threshold was calculated. In other words, did the calculation take place when SIOC was first enabled, or is there regular on-going calculations?
I’m delighted to be involved in an upcoming project on vSphere Design Considerations. This is the brain-child of my ex-colleague, Frank Denneman, who recently fu^H^H decided to broaden his horizons and join an interesting new start-up called PernixData. 🙂 Also on the project are Duncan Epping (still a colleague), Jason Nash and the inimitable Vaughn Stewart of NetApp. To cut to the chase, the objective here is to create a pocket-sized book containing the best vSphere design considerations. However, the cool part of this book is that the community are the authors. And the book will be free, courtesy of…
This is something that was recently brought to my attention, and I wasn’t aware of this difference in behavior between the various storage vendors who implement VAAI-NAS. VAAI-NAS implements a number of different offload primitives, but the one we are interested in here is the Fast File Clone primitive which is the ability to offload the creation of snapshots/clones to the NAS storage array. This mechanism is also referred to as Native Snapshots. However, some arrays cannot support a full chain of snapshots.
I’ve blogged about the VMFS heap situation numerous times now already. However, a question that I frequently get asked is what actual happens when heap runs out? I thought I’d put together a short article explaining the symptoms one would see when there is no VMFS heap left on an ESXi host. Thanks once again to my good friend and colleague, Paudie O’Riordan, for sharing his support experiences with me on this matter – “together we win”, right Paud?
I just got a notification about this myself today. Apparently there is some interoperability issues with VAAI (vSphere APIs for Array Integration) & EMC RecoverPoint on EMC VNX arrays. It looks like the VNX Storage Processor (SP) may reboot with Operating Environment Release 32 P204 in a RecoverPoint environment. EMC have just released today a technical advisory – ETA emc327099 – which describes the issue in more detail but is basically advising customers to disable VAAI on all ESXi hosts in the RecoverPoint environment while they figure this out. Hopefully it won’t take too long to come up with a…
Thanks to our friends over at EMC (shout out to Itzik), we’ve recently been made aware of a limitation on our UNMAP mechanism in ESXi 5.0 & 5.1. It would appear that if you attempt to reclaim more than 2TB of dead space in a single operation, the UNMAP primitive is not handling this very well. The current thought is that this is because we have a 2TB (- 512 byte) file size limit on VMFS-5. When the space to reclaim is above this size, we cannot create the very large temporary balloon file (part of the UNMAP process), and…