So a a backup command with four(4) to disk specifications will have four writers and a reader. You get a writer per backup device, each retrieving from the data queue. The writer(s) pull filled data buffers from the data queue, process the buffer and return it to the free list. The reader pulls a free buffer, fills it with data and places it on the data queue. The buffers are transitioned between the free and data queues. Details about the calculation are located in: The target is commonly 4MB for each buffer resulting in approximately 4 to 8 buffers.
When a backup starts it creates a series of buffers, allocated from the memory outside the buffer pool. On an x86 installation the calculation results in ~386MB left outside the buffer pool.īackup and restore work very similar so I will only cover the backup example in this post. The remaining virtual address space has been referred to as memory outside buffer pool and memory to leave (Ģ56MB + (sizeof(stacks) * max worker threads) SQL Server uses the majority of the memory for the buffer pool. You can use solutions that place the backup on alternate storage, snapshots, use compression and other alternatives.Ī common issue Microsoft SQL Server support sees is out of memory conditions. This means you don't have to use the built in SQL Server output destinations. The virtual device interface (VDI) backups allow 3rd party back-up solutions to integrate with the SQL Server.
As I do this I thought I would try to propagate some of this information on the blog. The Senior Escalation Engineers do various training and mentoring activities.
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