A quick note to let you know that I am co-presenting on an upcoming VMUG webinar with my good pal, Cody Hosterman, from Pure Storage. The subject is vSphere 6.5 Core Storage, and this is very much the same topic that we presented at VMworld 2017. We will cover new limits, deed dive into VMFS-6 and VAAI enhancements (including automated UNMAP), cover what’s new in NFS and iSCSI, and then finish with an overview of what we’ve done in the NVMe space. The webinar takes place on Thursday, November 16, 2017 at 11:00 AM US Central Standard Time. Cody and…
My Storage Policy Based Management (SPBM) presentation slide deck is now available online. This is the presentation that I delivered at a number of VMUG (VMware User Group) meetings this year in Europe, primarily Norway and Poland. SPBM is an integral part of VMware’s software defined storage vision, and is deeply integrated into vSAN, Virtual Volumes (VVols) and VAIO, the vSphere APIs for I/O Filters. Hope you find it useful. 2017 VMUG Storage Policy Based Management from Cormac Hogan
A quick note to let you know that the session that I delivered on day 1 of VMworld 2017 is now available on YouTube. The session is entitled “A Deep Dive into vSphere 6.5 Core Storage Features and Functionality” and I delivered this with Cody Hosterman of Pure Storage. Judging by the feedback, and the number of passing comments I received in the hallways at VMworld over the past 2 days, it seems that this session was very well received indeed. Hope you like it.
Does anyone remember the ATS Miscompare issue? This blog post from 2 years ago might jog your memory. It is basically an issue that arose when we began using ATS, the VAAI Atomic Test and Set primitive, for maintaining the ‘liveness’ of a heartbeat in vSphere 5.5U2. After making this change, a number of customers started to see “ATS Miscompare detected between test and set HB images” messages after upgrading to vSphere 5.5U2 or later. The HB reference in the message is shorthand for heartbeat. In previous releases, we did not use ATS for maintaining the ‘liveness’ of a heartbeat.…
Along with other improvements to VMFS-6, there is also a new block allocation mechanism which aims to reduce lock contention between hosts sharing the same VMFS-6 filesystem. To understand how lock contention could arise, it is important to understand that resources on VMFS are grouped into resource clusters; this is the same for VMFS-6 and earlier versions on VMFS. Resources could be file descriptors, sub-block, file block, pointer blocks, and so on. Historically, we have always tried to allocate different resource clusters to different ESXi hosts, which meant that only VMs running on the same host shared resources within the…
Something that I only just recently noticed is that we have made a change to the sub-blocks structure on VMFS-6, compared to VMFS-5. Sub-blocks are small allocations on a VMFS volume, and they are used to back small files. They were introduced as a space-saving measure to prevent using a full file block to back a very small file. To put this simply, when a file is created on VMFS, it is initially backed by a sub-block, and when the file grows above the size of a sub-block, it is switched to being backed by a file block (this has…
When vSphere 6.5 released towards the end of 2016, it introduced a brand new version of VMFS, VMFS-6. VMFS probably needs little in the way of introduction at this stage, it being VMware’s flagship filesystem for over 10 years at this point. There is an older VMFS whitepaper available here if you are new to VMFS and want to get more of an overview. Now VMFS-6 introduces two new internal block sizes concept for file creation. These are referred to as LFB (Large File Blocks) and SFB (Small File Blocks) and are used to back files on the VMFS-6 volume.…