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We got "device overload" error after the program ran successfully on production for a few months. And we find that some maps' sizes are very big, which may be bigger than 1,000.

After I inspected the source code, I found that the reason of "devcie overload" is that the write queue is beyond limitations, and the length of the write queue is related to the effiency of processing.

So I checked the "particle_map" file, and I suspect that the whole map will be rewritten even if we just want to insert one pair of KV into the map.

But I am not so sure about this. Any advice ?

Jiayi Liao
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1 Answers1

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So I checked the "particle_map" file, and I suspect that the whole map will be rewritten even if we just want to insert one pair of KV into the map.

You are correct. When using persistence, Aerospike does not update records in-place. Each update/insert is buffered into an in-memory write-block which, when full, is queued to be written to disk. This queue allows for short bursts that exceed your disks max IO but if the burst is sustained for too long the server will begin to fail the writes with the 'device overload' error you have mentioned. How far behind the disk is allowed to get is controlled by the max-write-cache namespace storage-engine parameter.

You can find more about our storage layer at https://www.aerospike.com/docs/architecture/index.html.

kporter
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