Dell Products Inc.

Emc IP Holding Company LLC

Ami Sabo

Vladimir Shveidel

Dror Zalstein

Vamsi K Vankamamidi

Bar David

Oran Asher Baruch

In at least one embodiment, processing can include determining, by a first node, an update to a metadata (MD) page, wherein the first node includes a first cache; sending, from the first node to a second node, a commit message including the update to the MID page; receiving, at the second node, the commit message from the first node; and storing, by the second node, an updated version of the MID page in a second cache of the second node only if the second cache of the second node includes a cached copy of the MD page, wherein the updated version of the MID page, as stored in the second cache of the second node, is constructed by applying the first update to the cached copy of the first MD page.

Techniques for maintaining cache coherency

A method, computer program product, and computer system for controlling, by a computing device, access to a non-volatile memory using a non-volatile lock as a reader of the non-volatile memory. Metadata (MD) non-volatile memory commits may be throttled until capacity of the non-volatile memory is at a threshold capacity.

System and method for non-disruptive upgrade for metadata log with minimal hiccup

In at least one embodiment, processing can include receiving a metadata (MD) update for a MD page, wherein the MD update has an associated type; determining whether the type is a custom MD type; responsive to determining the type is a custom MD type, performing first processing including: determining a custom bucket handle for the MD update based at least in part on the type and a logical index (LI) uniquely identifying the MD page; and applying the MD update to a custom bucket associated with the custom bucket handle; and responsive to determining the type is a custom MD type, performing second processing including: determining a regular bucket handle for the MD update based at least in part on the LI of the MD page; and applying the MD update to a regular bucket associated with the regular bucket handle.

Techniques for performing metadata updates

Techniques for reconstructing or building metadata pages in storage nodes that have a delta-log based architecture. The techniques include walking 'up' an ancestor chain of a metadata page, detecting the most recent delta update for a metadata entry of the metadata page, writing the most recent delta update to a location of the metadata entry in the metadata page, setting a bitmap entry corresponding to the location of the metadata entry in the metadata page, detecting a less recent delta update for the metadata entry of the metadata page, and, having previously set the bitmap entry corresponding to the location of the metadata entry in the metadata page, avoiding writing the less recent delta update to the location of the metadata entry in the metadata page. In this way, the need to save in memory the entire ancestor chain of the metadata page can be eliminated.

One path metadata page reconstruction with no dynamical memory allocation for delta-log based storage

In a log based system, a reclamation list of cache pages containing dirty data can be maintained and used. The cached dirty data pages identified by the reclamation list can be candidates for eviction from the cache. A cached dirty data page on the reclamation list can be persistently logged in a transaction log extension having storage allocated from a non-volatile solid state drive (SSD). The reclamation list can include descriptors of the cached dirty data pages prioritized for eviction in accordance with a least recently used (LRU) policy so that the LRU cached dirty data page can be selected for eviction. When a dirty data page which was evicted from the cache is reloaded into cache, the dirty data page can be added to the reclamation list by adding its page descriptor to the reclamation list. A dirty data page can be removed from the reclamation list once flushed.

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Netanya, Israel

Ami Sabo