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Cache strategy needed by turning off write cache on harddisk device
Posted: Mon Dec 10, 2018 6:02 pm
by Cybermage
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I have the following configuration 2x 10 TB x300 toshiba harddisk's 1 x 2 TB 970 evo SSD.
L1 cache of 16 GB and and L2 cache of 1.42 TB and it works very good.
I have Cache hit rates of 98% when using starting virtual machines.
as inspiration of the following topic
https://www.romexsoftware.com/bbs2/en-u ... =33&t=4667
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i start experimenting to turn off the write cache on of my Toshiba 10 TB harddisk
then i copy a directory with files of the size in total of 280 GB the speed drops from 200 MB/s to 70 MB/s per second.
the directory contains files of diffent file sizes.
if there a way to of better handeling the write cache by primocache?
Please some advise on this matter.
Re: Cache strategy needed by turning off write cache on harddisk device
Posted: Mon Dec 10, 2018 10:15 pm
by Jaga
I've been told by Romex support in the past to simply leave the Windows write-caching algorithm at it's default setting. Enable write caching in that interface, but leave write-cache buffer flushing off.
Re: Cache strategy needed by turning off write cache on harddisk device
Posted: Tue Dec 11, 2018 1:29 pm
by Cybermage
Did some more experimenting and when i turn off write cache and turn on Defer write i got the same speed 200 MB/s. Only in the beginning the speed is higher think it is the burst.
Re: Cache strategy needed by turning off write cache on harddisk device
Posted: Thu Dec 13, 2018 3:11 am
by Support
Windows write caching is happened on file system level which is handled first before PrimoCache disk level. When you turn off Windows write caching, file system will directly deliver write-data to disk, this takes some process time and causes speed down.