Switching the default implementation of disk buffers to
After much testing, we’re promoting
disk_v2 to stable to bring performance and efficiency benefits to everyone using disk buffers.
Back in February, we announced the beta release of our new, reworked disk buffer implementation –
disk_v2 buffer – as part of Vector 0.20.0. Today, we’re excited to announce that
disk_v2 is now considered stable and is being promoted to the default implementation for
As part of reworking the implementation of disk buffers, we needed to write the new implementation alongside the existing disk buffers. This was necessary so that we could build confidence in the new implementation before making it the default, as well to provide us time to write the necessary documentation and migration procedures and so on.
We called the new implementation
disk_v2 to distinguish it from
disk. You were able to specify
this in your buffer configuration to opt in to using them when in beta. Now that we’re comfortable
marking the new implementation as stable, we’ve changed their name so that
disk_v2 is now
and what used to be
disk is now
While there were many reasons to write a new implementation of disk buffers – fewer code
dependencies, more consistent performance, better guarantees around data durability – we’ve tried
to keep the user experience foremost in our minds: switching to using
disk_v2 should be as
painless as possible.
When running Vector 0.22.0, if we detect a disk buffer that was created with the old
implementation, Vector will seamlessly migrate it to the new
disk_v2 format and use the new format
This does come with a few caveats:
- Vector needs free space to write into the new buffer as it’s migrating the old buffer over
- Vector will delete the old buffer once all records have been migrated
While we do try to maximize buffer compaction during the migration – basically, delete old data as it’s migrated – the process is eventually consistent, and migration won’t always stay at or below the configured maximum buffer size. With this in mind, it is best to plan for having free space beyond the configured maximum buffer size limit – in practice, 10 to 15% extra is sufficient – to allow the migration to complete successfully.
Additionally, as the migration process is destructive – the old buffer is migrated and then removed
– you may wish to make a copy of the buffer data directories (located under the
specified in your configuration) before running Vector 0.22.0. This will allow you to roll back to
Vector 0.21 (or earlier) if necessary.
We’re still just as excited about the performance improvements to disk buffers, and have exciting plans for extending buffering capabilities as a whole. If you have any feedback for us, whether it’s related to the new disk buffers or anything else, let us know on Discord or on Twitter.