Bad Blocks

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FlaParrotHead
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Bad Blocks

Post by FlaParrotHead » Thu Aug 15, 2019 5:14 am

Bad Block Scan completed and reports 15 bad blocks found. Is there a tool that can repair them? How worried should I be? 1 of 3 6tb WD red drives in bays 1-3 of a TVS-471. Thanks!


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dolbyman
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Re: Bad Blocks

Post by dolbyman » Thu Aug 15, 2019 5:18 am

RAID scrubbing would repair them, but do you really want to trust any HDD with bad blocks ? .. what if another drive fails ? (rebuild from defective blocks will not work)

I'd replace it sooner rather than later

FlaParrotHead
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Re: Bad Blocks

Post by FlaParrotHead » Thu Aug 15, 2019 5:49 am

dolbyman wrote:RAID scrubbing would repair them, but do you really want to trust any HDD with bad blocks ? .. what if another drive fails ? (rebuild from defective blocks will not work)

I'd replace it sooner rather than later
Thanks... I’ll scrub for now and see about getting some new drives. I am out of the US and getting drives is a long slow process. I currently have slots 1-3 configured as RAID5 using 3 WD 6tb drives. Slot 4 is a separate stand alone drive. Is there a good doc or simple instructions as to how to swap old for new drives without loosing data/configurations. I have only done the initial build, several years ago, and never upgraded or needed to swap drives. Thanks!


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dolbyman
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Re: Bad Blocks

Post by dolbyman » Thu Aug 15, 2019 6:07 am

the online manual explains it pretty well

TL:DR hotswap a new drive (of equal or larger size) and rebuild will start automatically

jsteng
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Re: Bad Blocks

Post by jsteng » Thu Aug 15, 2019 8:18 am

From what I know HDs have several reserved tracks for Bad Blocks.
Does SMART 197, 198 errors mean "no more reserved tracks" to substitute bad blocks?

How frequent should we do Scrubbing? From my understanding, we should at least do this once a week, and immediately upon Bad Block discovery. But what is the best practice?

And lastly, what exactly does QNAP do during RAID Scrubbing? And how does it recover errors?

Thanks.

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MrVideo
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Re: Bad Blocks

Post by MrVideo » Fri Aug 16, 2019 9:02 am

If the HDD hits a bad sector during a read and it can't recover from it via the CRCC, then there is no getting that data back, period. The unrecoverable error should be logged by the NAS. That HDD needs to be replaced immediately. Recoverable errors are a bad sign, indicating that the HDD is going to end up failing. Get it replaced immediately.
QTS 4.1.n/4.2.n/4.3.n MANUAL
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QNAP md_checker nasreport (release 20180525)
===============================
Model: TS-869L -- RAM: 3G -- FW: QTS 4.1.4 Build 20150522 (used for data storage)
WD60EFRX-68L0BN1(x1)/68MYMN1(x7) Red HDDs -- RAID6: 8x6TB -- Cold spare: 1x6TB
Entware
===============================
Model: TS-451A -- RAM: 2G -- FW: QTS 4.2.3 Build 20170213 (used as a video server)
WL3000GSA6472(x3) White label NAS HDDs -- RAID5: 3x3TB
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FlaParrotHead
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Re: Bad Blocks

Post by FlaParrotHead » Fri Aug 16, 2019 12:45 pm

Just takes time, effort, and additional cost when living outside of the world of Amazon, tech stores, and easy access to things...


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