Destaging metadata log updates with an adaptive phase one destage merging approach

A system comprising:

• one or more processors;
• and
• one or more memories comprising code stored thereon that, when executed, performs a method of
• receiving a plurality of metadata (MD) updates for a plurality of MD pages;
• recording the plurality of MD updates for the plurality of MD pages in a MD log;
• and
• performing a first destaging phase for the plurality of MD updates of the MD log including:
• determining, in accordance with one or more merge criteria, whether to merge the plurality of MD updates with an existing tablet persistently stored in a tablets tier, wherein the existing tablet includes a first set of buckets, each having a first bucket size;
• responsive to determining to merge the plurality of MD updates with the existing tablet, performing merge processing including:
• merging the plurality of MD updates of the MD log with the existing tablet;
• generating, as a result of said merging, a merged tablet;
• and
• storing the merged tablet persistently in the tablets tier;
• responsive to determining not to merge the plurality of MD updates with the existing tablet, performing first processing including:
• persistently storing the plurality of MD updates as a new tablet in the tablets tier without merging the plurality of MD updates with the existing tablet;
• determining a merged bucket size of the merged tablet, wherein the merged tablet includes a second set of buckets, each having the merged bucket size;
• determining, based at least in part on the merged bucket size, a first amount of storage needed for the merged tablet;
• determining, based on the first amount, whether the tablets tier has sufficient free storage for storing the merged tablet;
• and responsive to determining that the tablets tier does not have sufficient free storage for storing the merged tablet, performing said first processing that persistently stores the plurality of MD updates as the new tablet in the tablets tier without merging the plurality of MD updates with the existing tablet.

A non-transitory computer readable medium comprising code stored thereon that, when executed, performs a method comprising:

• receiving a plurality of metadata (MD) updates for a plurality of MD pages;
• recording the plurality of MD updates for the plurality of MD pages in a MD log;
• and
• performing a first destaging phase for the plurality of MD updates of the MD log including:
• determining, in accordance with one or more merge criteria, whether to merge the plurality of MD updates with an existing tablet persistently stored in a tablets tier, wherein the existing tablet includes a first set of buckets, each having a first bucket size;
• responsive to determining to merge the plurality of MD updates with the existing tablet, performing merge processing including:
• merging the plurality of MD updates of the MD log with the existing tablet;
• generating, as a result of said merging, a merged tablet;
• and
• storing the merged tablet persistently in the tablets tier;
• responsive to determining not to merge the plurality of MD updates with the existing tablet, performing first processing including:
• persistently storing the plurality of MD updates as a new tablet in the tablets tier without merging the plurality of MD updates with the existing tablet;
• determining a merged bucket size of the merged tablet, wherein the merged tablet includes a second set of buckets, each having the merged bucket size;
• determining, based at least in part on the merged bucket size, a first amount of storage needed for the merged tablet;
• determining, based on the first amount, whether the tablets tier has sufficient free storage for storing the merged tablet;
• and
• responsive to determining that the tablets tier does not have sufficient free storage for storing the merged tablet, performing said first processing that persistently stores the plurality of MD updates as the new tablet in the tablets tier without merging the plurality of MD updates with the existing tablet.