VMware Cloud on AWS: Deploy and Manage 2019.VMware Workspace ONE: Advanced Integration.VMware Horizon 7: Install, Configure, Manage.VMware NSX-T Data Center: Troubleshooting and Operations.VMware NSX-T Data Center: Install, Configure, Manage.VMware vSphere: Optimize and Scale – NEW !!!.VMware vSphere: Install, Configure, Manage – NEW !!!.Using this controller is not recommended until the fix is available.Ī live document on storage controllers for VSAN (on which this article is based) was created by our VSAN PM, Kiran Madnani, and lives here:Ĭheck this document regularly for updates on VSAN and Storage Controllers. This is a known issue only with this specific controller, and that a fix is on its way shortly. The VSAN team is actively looking at this issue. This could result in data loss and VSAN becoming unavailable. This manifests itself as disks/controller going into degraded mode and resulting in PDL (Permanent Device Loss). RAID Controllers (that do not support pass-through mode): HP Smart Array P420iĪre there any known issues with storage controllers?Ĭurrently, the AHCI SATA controller has known issues with VSAN.
Pass-through controllers: Dell Perc H310, HP H220i, IBM ServeRAID M1015 SAS/SATA Controller, Dell Perc H200, LSI 2008
The following storage controllers have been tested so far: Though IOs will be failed back correctly to the guest VMs, VSAN won’t detect that this is a APD/PDL condition and hence the fail-over will be handled differently by VSAN.Īre there controllers VMware is internally testing with Virtual SAN? In addition, a hot-plug remove of the drive will not be propagated back to VSAN. In order to use the disk with VSAN, one would need to carve out a logical RAID device/LUN using the RAID controller’s utility before it is consumed by the VSAN datastore. This means that a hot-plug event will not be recognized by VSAN. If pass-thru mode is not supported by the controller, VSAN may not function in “Auto” mode. Performance on the VSAN datastore will not be maximized in this configuration.īesides performance, is there any functionality lost with a controller that does not support pass-through mode? Since VSAN doesn’t control the device directly, the proximal IO algorithm built into VSAN will not function efficiently. If the RAID controller does not support pass through mode, VSAN will still work. Will a RAID controller that does not support pass-through mode work with VSAN? The VSAN proximal IO algorithm turns the random I/O from the I/O blender back into sequential I/O, thus improving performance. This design addresses the “I/O blender” situation where sequential I/O from a VM can become random when multiple VM are doing I/O to the same disk. The proximal IO algorithm is used to de-stage writes from the Flash device that is “approximately” close to each other on the magnetic disk. To do so, VSAN implements a proximal IO algorithm. VSAN directly manages the magnetic disks, published via the pass-thru controller, in a way that the limited IOPs on the magnetic disk are used in the most optimal way. While magnetic disk drives provides a low $/GB, they only support limited IOPs. This design obtains the lowest $/GB (using magnetic disks) and the lowest $/IOP (using Flash). All writes go to the flash layer, and all reads are first tried from the flash layer.
VSAN uses magnetic disks as the persistent store for the data on the VSAN datastore and Flash as a performance acceleration layer – a read cache and write buffer – in front of the magnetic disks. Why are RAID controllers with pass-through support recommended? However, for RAID controllers, VSAN works best if the controller supports pass-through mode. In general, we encourage beta participants to use any storage controller with Virtual SAN.