A common recommendation from storage vendors is to change the default IOPS setting for VMwares’ Native Multi-Pathing (NMP) Path Selection Policy (PSP) Round Robin. The IOPS setting controls how many I/Os are sent down a single logical path before switching to the next path. By default this number is 1,000 I/Os. The VMAX recommendation is to set this to 1. The purpose of this blog post is not to debate the setting, but to help those who want to use it. Regardless, I have seen many customers benefit from this recommendation. Once they see a benefit they want to know–can I make this setting a default?
This is a topic that I get asked about a lot and a recent internal email thread prompted me to write a post about it. On a Symmetrix array if you want a volume larger than 240 GB you need to create a metavolume. When creating a metavolume you have two configuration choices; concatenated or striped. There are many benefits to striped over concatenated (all of them performance-related) but one disadvantage. Due to their nature striped metavolumes are harder to expand. Until a few years ago thin striped metas couldn’t even be expanded online. So the decision was easy–do you think you will need to expand or not. In Enginuity 5875 and Solutions Enabler online expansion of striped metavolumes was allowed.
As you may or may not be aware, I am the sole author of the SRDF Storage Replication Adapter for VMware Site Recovery Manager Techbook. The Techbook for those of you who haven’t used it or aren’t aware of EMC Techbooks is a implementation guide for SRDF with SRM. Best practices, how-to, hints, etc.
EMC offers a variety of tools to manage/enhance your virtual or physical environments–some free, some licensed. In most cases when you think of EMC tools for VMware one conjures up the free Virtual Storage Integrator which is more commonly referred to as VSI.
VSI is a great tool and continues to be improved through each version and allows you to provision storage, manage pathing, configure SRM etc. The one thing it does not have is a way to automate these tasks through an API or CLI. This is where another product comes in–one that many do not associate with VMware. The EMC Storage Integrator (ESI) is a lot of times seen as the Microsoft version of VSI–but that isn’t really true at all. While it might have started out that way and does indeed support Hyper-V and has a ton of Microsoft-specific features it is really the heterogeneous storage integrator. Importantly it has a very handy and powerful feature–PowerShell cmdlets.
One of the documents that my colleague Drew Tonnesen (@drewtonnesen) and I maintain is a white paper that explains the how, what, why, when, etc. of using VMware’s VAAI block primitives (WRITE SAME, XCOPY, ATS and UNMAP) with Symmetrix VMAX storage systems. We update this document around twice a year or as needed to take into account new Enginuity releases or VMware releases. We just posted the latest update this weekend on EMC’s website:
As many are probably aware, RecoverPoint 4.0 recently released support for Point-In-Time test recovery and recovery for VMware vCenter Site Recovery Manager. In conjunction with the RP SRA and the Virtual Storage Integrator (VSI) users can select a PiT in the past instead of automatically being forced to use the latest copy.
Since this came out (and many times prior) I have been asked can we do this with the SRDF SRA and TimeFinder along with VMware SRM? The answer is yes! The process though is somewhat different of course. By far this question is mostly targeted for test recovery only, as most conversely prefer up-to-date images when they actually failover. So this post will focus on test recovery. Continue reading Point-in-time test recovery with SRDF and VMware SRM→
Migrating a virtual machine that uses 100% virtual disks is a simple task due to VMware Storage vMotion but migrating a VM that uses Raw Device Mappings from one array to another is somewhat trickier. There are options to convert a RDM into a virtual disk but that might not be feasible for applications that still require RDMs to be supported. Other options are host based mechanisms/in-guest mechanisms to copy the data from one device to another. That option sometimes can be complex and requires special drivers or even possibly downtime to fully finish the transition. To solve this issue for physical hosts, EMC introduced for the Symmetrix a feature called Federated Live Migration.
Federated Live Migration (FLM) allows the migration of a device from one Symmetrix array to another Symmetrix array without any downtime to the host and also does not affect the SCSI inquiry information of the original source device. Therefore, even though the device is now residing on a completely different Symmetrix array the host is none the wiser. FLM leverages Open Replicator functionality to migrate the data so it has some SAN requirements–the source array must be zoned to the target array. A FLM setup looks like the image below: