Pw.x Manual
Rosalie Checca
Next step is our band calculation (non-self consistent field) calculation. Thebands calculation is non self-consistent and reads/uses the ground stateelectron density, Hartree, exchange and correlation potentials obtained in theprevious step (scf calculation). In case of non self-consistent calculation, thepw.x program determines the Kohn-Sham eigenfunction and eigenvalues withoutupdating Kohn-Sham Hamiltonian at every iteration. We need to specify thek-points for which we want to calculate the eigenvalues. You may use theSee-K-path tool by materials cloud to visualize the K-path. Wecan specify nbnd, by default it calculates half the number of valenceelectrons, i.e., only the occupied ground state bands. Usually we are interestedalso in the unoccupied bands above the Fermi energy. Number of occupied bandscan be found in the scf output as number of Kohn-Sham states. Below is asample input file for the band calculation:
Usually, band gaps computed using common exchange-correction functionals such asLDA or GGA are severely underestimated compared to actual experimental values.This discrepancy is mainly due to (1) approximations used in the exchangecorrection functional and (2) a derivative discontinuity term, originating fromthe density functional being discontinuous with the total number of electrons inthe system. The second contribution is larger contributor to the error. It canbe partly addressed by a variety of techniques such as the GW approximation.
Strategies to improve band gap prediction at moderate to low computational costnow been developed by several groups, including Chan and Ceder (delta-sol)1,Heyd et al. (hybrid functionals)2, and Setyawan et al. (empirical fits)3.
AWS users can now deploy Portworx with the PX-StoreV2 datastore. In order to have PX-StoreV2 as your default datastore, your cluster should pass the preflight check, which verifies your cluster's compatibility with the PX-StoreV2 datastore.
You can now provision and use cloud drives on FlashArrays that are in the same zone using the CSI topology for FlashArray Cloud Drives feature. This improves fault tolerance for replicas, performance, and manageability for large clusters.
For environments such as GCP and Anthos that follow blue-green upgrade model, Portworx allows temporary license extension to minimize downtime during upgrades. Once you start the license expansion, the Portworx cluster's license will temporarily be extended to accommodate up to double the number of licensed nodes. While the existing nodes (called blue nodes) serve production traffic, Portworx will expand the cluster by adding new nodes (called green nodes) that have upgraded Linux OS or new hardware.
Portworx now offers the capability to utilize user-managed keys for encrypting cloud drives on Oracle Cloud Infrastructure Container Engine for Kubernetes (OKE). By leveraging powerful encryption algorithms, the Oracle disk encryption feature converts data into an encrypted format, ensuring that unauthorized individuals cannot access it. You can specify the encryption key in the StorageCluster using the following cloud-drive volume specifications:type=pv-,size=,kms=
Portworx now enables you to define custom tags for cloud drives provisioned across various platforms such as AWS, Azure, GCP, and Oracle cloud. While installing Portworx, you can specify the custom tags in the StorageCluster spec: type=,size=,tags=This user-defined metadata enhances flexibility, organization, and provides additional contextual information for objects stored in the cloud. It empowers users with improved data management, search capabilities, and greater control over their cloud-based data.
Portworx can now be deployed from the GCP Marketplace with the following new offerings. You can also change between these offerings after deploying Portworx by changing the value of the environment variable PRODUCT_PLAN_ID within your StorageCluster spec:
A known issue with multipath tool versions 0.7.x to 0.9.3 causes high CPU usage and/or multipath crashes that disrupt IO operations. To prevent this, Portworx now performs a prerequisite check to detect these faulty multipath versions starting with version 2.13.0. If this check fails, it will not be possible to install or upgrade Portworx. Portworx by Pure Storage recommends upgrading the multipath tool version to 0.9.4 before upgrading to Portworx to any Portworx 2.13 version.
On-prem users can now enable PX-Fast functionality that utilizes the new PX-StoreV2 datastore. PX-Fast enables a new accelerated IO path for volumes and is optimized for workloads requiring consistent low latencies. PX-StoreV2 is the new Portworx datastore optimized for supporting IO intensive workloads for configurations utilizing high performance NVMe class devices.
Metro and asynchronous disaster recovery (DR) involves migrating Kubernetes resources from a source cluster to a destination cluster. To ensure that the applications can come up correctly on the destination clusters, you may need to modify resources to work as intended on your destination cluster. The ResourceTransformation feature allows you to define a set of rules that modify the Kubernetes resources before they are migrated to the destination cluster.
User Impact: Previously, rolling upgrades of customer environments in cloud auto-scaling groups may have exceeded licensing quota if storageless nodes were created before offline nodes were removed from the cluster. With 2.1.2, offline nodes no longer count against licensing count.
Recommendations: Upgrade to 2.1.2 to support rolling upgrades in cloud auto-scaling environments. If you are unable to upgrade to 2.1.2, you can work with Portworx support to get temporary licenses that increase the node count until an upgrade to 2.1.2 can be planned.
User Impact: Previously, attempting to attach too many drives results resulted in errors. With 2.1.2, Portworx introduces a maximum limit of 12 drives per node, and will respond to attempts to add more than 12 drives with the following error: cannot provide more than 12 number of drives per node.
User Impact: The internal KVDB tracks peer URLs as potentially ephemeral IP addresses. If the entire cluster becomes unavailable in an outage, Portworx may be unable to reconnect. With 2.1.2, internal KVDB now keeps track of nodes using a DNS, and can therefore reconnect in the event of a total cluster outage.
User Impact: Previously, if you did not specify an enforcement type in VolumePlacementStrategy, PVC creation failed. With 2.1.2, Portworx will default to enforcement: required if you do not specify an enforcement type.
Customer Impact: Adding a journal device which is LVM drive partition will fail but the error is not clear in the logs. In general, it is not recommended to use LVM partitions as journal devices because of the performance limitations of such devices.
Issue: PWX-9055 - Installing Portworx with an LVM volume that has a similar name to another LVM volume will deactivate the other LVM volume (not used by Portworx). For e.g, if Portworx is asked use to /dev/mapper/volone and there is another LVM volume with the name /dev/mapper/volone1, volone1 would get deactivated.
Recommendations: Portworx by Pure Storage recommends inspecting the system beforehand and to use volume names for LVM volumes that do not overlap with the existing volumes. To completely avoid the issue, Portworx recommends upgrading to 2.0.3.7.
Customer Impact: When a user tries to add a journal device to a storage-less node right after adding a storage device, Portworx might crash and restart. In general, there is no application error as Portworx restarts within the 10 min device timeout interval, but there may be a very brief slow down of the I/Os.
Customer Impact: This was seen in environments where there was heavy I/O with shared and non-shared volumes. Also, there were lots of replicas on the node to which a lot of traffic was being routed to. This resulted in a scenario where the internal credits were exhausted. 2.0.3.7 increased the credits and resource allocation.
Recommendations: Storage-less node must be restarted to release the resources so application I/O can begin to run. Resources used by volumes which are detached when the node was down are not released when the node comes back online. This was resolved so these resources are now properly released to the global internal resource pool in Portworx.
Recommendations: Users must double-check if they already have the same name that they are trying to add new secrets to the same cluster. 2.0.3.7 implemented a check to look for existing names before accepting a new secret. This prevents the secret from being overwritten.
Important note: Consul integration with 1.5.0 has a bug which results in Portworx querying a Consul Cluster too often for a non-existent key. We will be pushing out a 1.5.1 release with a fix by 08/31/2018
All customers on 1.2.x release will be able to upgrade to 1.4 but in a few specific cases might need a node reboot after the upgrade. Please reach out to support for help with an upgrade or if there are any questions if you are running 1.2.x in production.
Upgrade Note 3: Container information parsing code has been disabled and hence the PX-Lighthouse up to 1.1.7 version will not show the container information page. This feature will be back in future releases and with the new lighthouse
PWX-3544 Improvements to Portworx diagnostics - REST API to retrieve and upload diagnostics for a node or cluster. Diagnostics run using the REST API includes vmstat output and the output of pxctl cluster list and pxctl --json volume list. The diagnostics also include netstat -s before the node went down.
PWX-3859 After adding a volume template to an Auto Scaling Group and Portworx adds tags to the volume: If you stop that cluster and then start a new cluster with the same volume, without removing the tags, a message indicates that the cluster is already initialized. The message should indicate that it failed to attach template volumes because the tag is already used. You can then manually remove the tags from the stopped cluster.
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