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This is a known problem of Windows Server 2016 and further https://learn.microsoft.com/en-us/troub ... e-transfer.Copying large vhdx files takes almost twice as long as when I copy it directly to the raid volume.
Can you explain what 3x loopback and 2x partner iSCSI sessions mean?More detailed, I didn't understand,thanksyaroslav (staff) wrote:Hi,
Thanks for your questions.
Try adding 3x loopback and 2x partner iSCSI sessions. Also make sure write-back caching is off and you have no write-back caching on StarWind HA device's levels.
Copying is a different thing and unlike synthetic tests is bottlenecked by filling system buffers. To resolve it you need to change FirstBurstLength to 262144 in HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4d36e97b-e325-11ce-bfc1-08002be10318}\000X\Parameters
I have set high perfromance, is a bit better then bevor.yaroslav (staff) wrote:Jan,
Please make sure to have the BIOS performance profile set to high performance.
Try varying the ratio of read/write cache.
Do you see CPU overutilization during the test?
Try using Round Robin with a subset where most of the paths use partner connections (then repeat for local-only).
Will be waiting for more tests! Thanks!
what you mean with multiple iSCSI session to the target? i have in the iscsi initator 4 session to the partner, adding more makes no different. Sync ist currently one adapter one 10gbit are dedicated for sync and the other 10gbit is dedicated for iSCSI.yaroslav (staff) wrote:Hi,
That's interesting. Thanks for sharing!
Can you try multiple iSCSI sessions to the target when replication is enabled?
Can you try performance tests with a single sync adapter?
Also, can you try iSER for sync links?
yaroslav (staff) wrote:In Windows, you are connecting storage over 127.0.0.1 (loopback) and partner connections.
Local sessions might have different performance.
iSCSI sessions have limit in performance and a single iSCSI session may be slower than SSD. So, by adding more of them you increase the queue of the iSCSI stack.
In a nuthsell, try adding more iSCSI sessions to storage.