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SnowReborn
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Quick question regarding windows write cache vs primocache L1 defer write

Post by SnowReborn »

As far as I know, Windows default enables "Write-Caching policy" with "Enable write caching on the device".

I also believe there are two types of "write caching" for Windows(correct me if i am wrong):
1. "write back caching", seems to function similar to primocache's L1 deferred write. The write request go to RAM and is being flushed to target disk at a delayed time while marking the file write request as "complete".
2. "write through caching", which write into RAM but does NOT mark the write request as complete until all data from RAM is properly flushed to target disk.

It would be nice if someone can provide me a detailed article explaining how window's own "write caching" works, quick google didn't yield anything.

My question is, since windows has this cache enabled by default, How is primocache's L1 Deferred write different from Windows' write caching mechnism besides custom set timer delay? And if anyone knows please let me know which method "1 or 2" is used by windows write caching?

Also I would like to confirm if primocache's defer write is "write back caching", which marks the write request as complete.

Lastly, from a data integrity vs performance stand point, how does "write back" compared to "write through"? Thanks.

Also it seems like the time on the forum is dec 25th, so merry xmas!
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Re: Quick question regarding windows write cache vs primocache L1 defer write

Post by Support »

By default, Windows enables write-back caching at file-system level. It only has 2 second latency and users cannot tune anything.
PrimoCache Defer-Write is write-back caching at disk sector level. It can be customized, and it can make writes to be sequential as possible. Besides, PrimoCache can use SSD as cache, not only RAM, for Defer-Write.

Merry Christmas & Happy New Year!
BetoMattos
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Re: Quick question regarding windows write cache vs primocache L1 defer write

Post by BetoMattos »

It would be interesting to disable the "Enable write caching on the device" function, so for those who use Primocache?
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Re: Quick question regarding windows write cache vs primocache L1 defer write

Post by Support »

BetoMattos wrote: Mon Dec 04, 2023 2:47 pm It would be interesting to disable the "Enable write caching on the device" function, so for those who use Primocache?
It is recommended to use the default Windows policy in "Enable write caching on the device".
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