Blockbridge Version 5.1 updates the widely deployed 5.x AnyScale architecture. This release brings numerous performance and stability improvements alongside support for Proxmox, multi-cloud Openstack deployments, Grafana, and an updated Kubernetes driver. This post is current as of version 5.1.5. It incorporates all changes from the minor versions of 5.1 (5.1.1, 5.1.2, etc.)


Release 5.1.5 includes several improvements in management for both the web application and the command line tool.

  • CLI Roles and Levels: The CLI tool now offers a more focused workflow for tenants by appropriately restricting the visibility of administrative and infrastructure commands. Admins can further limit or expand the number of commands and options shown with levels like “advanced” and “expert” levels.
  • Hourly Roll-up Datastore Statistics: You can now view a robust set of utilization statistics from the CLI, via the “datastore stats” subcommand.
  • Enclosure and Volume Visibility: The web console now affords a more consistent and easier to navigate view of enclosures, volumes, and their underlying physical storage devices.
  • Grafana: Blockbridge now supports Grafana for dataplane statistics. Monitor every Blockbridge dataplane in your organization from a single Grafana dashboard, using the standard JSON datasource plugin.
  • Capacity-Scaled Burst IOPS Credits: You can now create service templates that scale the IOPS burst credit pool with the capacity of the provisioned volume.
  • Compression Scheduling: The dataplane now supports a daily schedule for performing data compression. It maintains a list of data segments to compress during the off hours, then processes them when the schedule permits.



Deploying Proxmox on Blockbridge just got a lot simpler. Release 5.1 brings full shared-block storage support for Proxmox with a supported plugin. Use the full suite of Blockbridge features:

  • High Availability
  • Multi-Tenancy & Multi-Proxmox
  • High Performance
  • At-Rest & In-Flight Encryption
  • Snapshots & Clones
  • Thin Provisioning & Data Reduction

Multi-Cloud Openstack

In 5.1, we’ve expanded the types of OpenStack deployments we can support. Prior versions of our Cinder driver were limited to one Openstack cloud per Blockbridge controlplane. The 5.1 release now includes support for multiple OpenStack clouds and per-tenant accounts.

Kubernetes Version 1.14

Our K8s driver version 2.0.0 is up to spec with Kubernetes 1.14.


Release 5.1 has benefited from a heavy focus on improving the performance of our compression-related metadata and the compression data cache.

  • Metadata Efficiency: On systems with a heavy re-write workload, database pages that store compression metadata could become inefficiently used, leading to increased lookup times. In 5.1, we have optimized the way our B+tree handles these pages yielding a much improved fill-factor and compact metadata layout.
  • Metadata Cache: Efficiency has improved more than 40% in release 5.1.
  • Metadata Concurrency: For large installations where the compression metadata exceeds the cache size, we’ve improved our database concurrency by more than an order of magnitude.
  • Data Cache Sweeping: We’ve taken steps to limit the impact of compression scans on the compressed data cache. These scans now use their own pool of cache memory, to avoid impacting cached user data.


We’ve improved performance across the board.

  • Snapshot Remove Fairness: Release 5.1 offers lower latency and higher IOPS for user traffic during snapshot removal (reclaim) metadata scans.
  • Offloaded Message Logging: The dataplane made strides in its low-level latency consistency by offloading its logging of diagnostic, user, and administrative events and statistics to another CPU core.
  • Improved Write-Combining: Some filesystems, including XFS, intersperse their inode metadata with user data. This forces client access patterns that are frequently not aligned with the Blockbridge extent size. Release 5.1 includes special handling to re-combine this sort of write pattern to achieve higher performance.
  • Micro-Optimizations: Several critical I/O handling codepaths in the dataplane have been hand-optimized to eliminate processor stalls due to excessive branching and memory references. And, we’ve markedly reduced some nasty instances of unnecessary data sharing between CPU cores. Translation: lower achievable latency and more IOPS headroom.
  • Client-Side Tunings: Release 5.1 includes enhanced support for client-side tunings on “host attach” over a wider range of 3.x, 4.x, and 5.x Linux kernels.
  • Adjustable TLS Compression: You can now adjust the TLS compression level of tunneled data sessions.
  • Lower Memory Fragmentation: We’ve improved our memory allocation techniques on the dataplane to avoid creating small, unusable sections of RAM, yielding more usable space for caching.
  • Improved Metadata Latency: Performance is up significantly for systems with heavy write workloads.

Snapshot Reclaim

Some workloads with partial overwrites of data segments cause patterns of space allocation such that some unneeded segments weren’t returned to the pool when their snapshots were removed. In 5.1.3, we’ve adjusted the snapshot reclamation algorithm to perform a deeper inspection for storage to be released, resulting in improved efficiency.


  • Linux Kernel 5.4.21: We’re currently shipping our own version of Linux kernel 5.4.21, based on the Long-Term Support (LTS) stream. We continue to monitor kernel development for activity related to NVMe support, network drivers, server platforms, and all block-layer bug fixes from upstream Linux. The bare-metal and cloud images include the blockbridge kernel built-in. Release 5.1.3 incorporates an important Kernel 5.4.21 Hotfix, adding the upstream kernel patch 6920cef (md/raid1: properly indicate failure when ending a failed write request). All Blockbridge 5.x series installs should upgrade. (Blockbridge 4.x installs are unaffected.)
  • Centos 7.9: The latest CentOS 7.9 release is now the base for all Blockbridge pre-built bare-metal and cloud images.
  • AMD EPYC Naples & Rome: With the 5.0 release, we began shipping installations specifically optimized for the AMD EPYC line of server processors. Release 5.1 continues this trend with optimizations to IRQ routing on 48- and 64-core AMD systems.
  • SCSI Enclosure Stability: Some Supermicro SCSI expanders manufactured in 2020 came with faulty firmware that would stop responding to SES enclosure queries. With support from our storage lab, Supermicro were able to address the issue. Older expanders are unaffected, but more recent models should be flashed to firmware revision or newer. Additionally, Blockbridge platform management software gained improved resiliency for managing SCSI enclosures.
  • Platform Memory Usage: Release 5.1 enforces tight constraints on the memory usage of platform-level services, leaving more memory for data and metadata caching.
  • Diskctl Enclosure View: Management of devices and volumes is significantly simpler with an enclosure-centric view that’s now the default in the “diskctl” command.
  • IP Addresses Scale: Doubled the number of supported front-facing IP addresses for data services.
  • iSCSI Sessions Scale: Doubled the number iSCSI sessions on a single target to support large multipath shared storage clusters.
  • Improved Failover and Service Move Times: We’ve improved the way that the Heal and Disk platform services coordinate on a service move action to improve the time to clean shutdown. And on startup or failover, the dataplane is quicker about opening and recovering volumes. Most failovers should be two to four seconds quicker.
  • Per-Volume Maintenance Mode: volumectl now supports setting a “maintenance mode” on a Heal volume to prevent the system from automatically replacing a failed drive.
  • NVMe Secure Erase: the disk service now provides a built-in interface to the nvme format command line tool.

Web UI

  • Statistics Widget: trimmed the significant figures shown in the tooltip back on some series.
  • Datastore Statistics: In 5.1.3, we significantly reworked the list of available statistics for the datastore to make the (long) list easier on the eyes. All the old favorites are there, and we’ve added a distinction between I/O’s measured at the QoS enforcement point vs. those in the core of the thin-provisioning controller.

Blockbridge Shell

The installation and management shell “blockbridge” now has much clearer, consistent organization, with better documentation.

  • Add a built-in workflow for configuring an HTTP proxy.
  • Do not need to stop services to remove a cluster fence.
  • In “vip del”, the list of VIPs is now sorted.
  • On service start or stop, shell warns if maintenance mode is enabled.

Bugs Fixed

  • We fixed an extremely rare case of stuck I/O requests on volumes with IOPS limits enabled.
  • Sending-side statistics for targets now properly count status PDUs.
  • Dataplane complex IOPS gauges were sometimes observed to oscillate by 10% when the rates were in the 100,000 IOPS range, or higher. This is fixed in 5.1.
  • Fixed a rare case where the iSCSI target discovery reply could be empty when interfaces were disabled.
  • Fixed instances where the datastore cache-hit statistic reported incorrect values under certain workloads.
  • Fixed a rare race condition that could cause cross-vss block clones to hang after a vdisk resize.
  • Fixed a race condition triggered by SCSI logical unit reset commands that in rare cases could cause I/O hang to a disk.
  • Fixed an unusual case where an overwrite of just-written data has to wait for the data journal to flush.
  • Fixed a startup memory allocation failure on systems with very large compressed record cache memory.
  • The cluster now tolerates link failures while in maintenance mode.
  • Fixed a parsing error that occurred after 9,999 iSCSI attaches on the same Linux host.
  • Fixed a parsing error with array check schedule times that had leading zeroes.
  • We closed an open internal HTTP port detected by Nessus. All Blockbridge internal services require certificate validation, so there was never any security risk.
  • We fixed a display issue where, during upgrade, some statistics series would occasionally show a large negative dip.