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Initial Configuration:

RAID:

  • Disk Drives: 6 HDD TOSHIBA MBF2600RC (600 Gb, 16 Mb, 10025 RPM, SAS, 600 Mb/s)

  • 2 Spans

  • Motherboard: SuperMicro X8DTU-6F+/6TF

  • RAID Controller: SuperMicro SMC2108

  • Virtual Group: RAID50

  • Polices:

    • Access: RW
    • Read: Normal
    • Disk Cache: Enable
    • I/O: Cached
    • Disable BGI: NO
    • Default Write: Write Through

Used Operation System: Windows Server 2016

Result:

CrystalDiskMark Metrics:

Read [MB/s]: 221.5

Write [MB/s]: 38.30

Ubuntu Live CD Metrics:

Read [MB/s]: 270.1

Write [MB/s]: 49.5

Question:

What can I attempt to increase Write Speed?

Should I reconfigure RAID50 settings, or configure different type of RAID?

AlGiorgio
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  • Is this a new array? What OS? One solution would be to not use "_hardware_" RAID... (which has other benefits too) – Attie Dec 19 '18 at 15:53
  • ["_Write Through_" vs "_Write Back_" caching](https://en.wikipedia.org/wiki/Cache_(computing)#Writing_policies) will likely affect this significantly, though make sure you have NV cache (or backup power) if you use Write Back. – Attie Dec 19 '18 at 15:55
  • So... 6 disks = 2 spans of 3 disks each? Try deleting and recreating the RAID. Use a live CD to test the I/O. You could always try a different RAID type to test. Doing three mirror sets and then I/O test against each might indicate if a drive is the culprit. You could also look to the RAID controller. Make sure you're on the most updated firmware for it from the vendor. – thepip3r Dec 19 '18 at 15:55
  • Thanks for response. I've updated my question to clarify your notes – AlGiorgio Dec 19 '18 at 16:06
  • @Attie, could you please tell what kind of 'Default Write' should I use to increase the speed? In accordance with the article you've sent Write-back is the faster case. Is it right? – AlGiorgio Dec 19 '18 at 16:09
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    Write Back will give you a higher write speed... until your cache fills up... but before enabling it you _must_ make sure that you have NVRAM or suitable backup power (e.g: battery / super cap). – Attie Dec 19 '18 at 16:16
  • https://serverfault.com/questions/339128/what-are-the-different-widely-used-raid-levels-and-when-should-i-consider-them – quadruplebucky Dec 19 '18 at 18:29

1 Answers1

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Changing Default Write policy to 'WRITE ALWAYS BACK' has aligned rate of speed:

Read [MB/s]: 222.6

Write [MB/s]: 208.8

So it's a good practice to consider this option for write intensive tasks.

AlGiorgio
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    Write-back cache substantially increases the risk of data loss in some use cases, as it does not guarantee that the data is written to permanent media (only to the cache) -- failure without a battery-backed cache is potentially damaging. – quadruplebucky Dec 19 '18 at 18:23