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June 24th, 2019 14:00
RAID scrub strategy On SCv2080?
We have a Scv2080 fully populated with 8TB HDDs. I recently noticed that at least 50% of the times when I opened Unisphere, RAID scrub is running in the background. I understand the lenght of it greatly depends on system load and disk performance, but could you fill me in about the typical frequency and duration of RAID scrub and how I can minimize the impact on my application?
Thanks!
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DELL-Sam L
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June 25th, 2019 09:00
Hello 5X5CX62,
Are you reffering to data progression? If that is the case, then data progression is all ways running so that it can move the data between your tiers. Here is the link to the administrator guide and if you look on page 63 it explains more about data progression. https://topics-cdn.dell.com/pdf/storage-sc2000_administrator-guide_en-us.pdf
Please let us know if you have any other questions.
DELL-Bob Mi
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June 25th, 2019 10:00
Hello 5X5CX62,
The Raid Scrub process runs continuously in the background checking the blocks of data, and also verifying that there is no issues with the Raid extents. This is normal and should not cause any issues during normal processes. Are you seeing some performance issues that you feel the Raid Scrub is causing? Or are you questioning what the process is and why it is running?
For Unisphere refer to page 27 of Unisphere and Unisphere Central 2018 R1 Administrator’s Guide under How Data Progression Works:
https://topics-cdn.dell.com/pdf/dell-storage-manager_administrator-guide6_en-us.pdf
NOTE: With SCv2000 series controllers, Data Progression moves data between RAID 10 and RAID 5/6 and restripes RAID, but does not move data between storage tiers.
5X5CX62
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June 25th, 2019 17:00
Hello Bob,
Thanks for your reply. It appeared that raid scrub is producing pretty sizable amount of IOPS on backend per Unisphere perf charts. However, given the fact that our R730 with 8*8T drives finishes scrub fairly quickly and yet at least 50% of the time I log on to the SCV2080, RAID scrub was runing, I am pretty curious if there's a difference in strategy that caused the difference. I also remember SCOS 7.3 lowered the frequency from once per week to once per month and therefore it's pretty bizzare I am able to find it scrubbing most of the time.
Wade
DELL-Bob Mi
2 Intern
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230 Posts
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June 26th, 2019 08:00
Hello Wade,
I would recommend to call in to support to have them check the logs, and compare this to the the IO Usage during the times Raid Scrub ran. It is also possible that you are seeing a false positive in the IO Usage graphs. Support can log in to your system and assist you in looking in to this.