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 Post subject: 20,000 reallocations and drive is still serviceable?
PostPosted: October 11th, 2021, 13:39 
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It used to be that WD's drives would hit a SMART threshold when the number of reallocated sectors reached 500.

Here is a WD40NDZW that has racked up 50,392 reallocations (= 6299 physical sectors):

Attachment:
WD40NDZW-11MR8S1_SMART.gif
WD40NDZW-11MR8S1_SMART.gif [ 130.06 KiB | Viewed 1557 times ]


The normalised value has dropped from 200 to 182, so this suggests that the drive is spec'ed for 20,000 reallocated physical sectors.

    50392 / 8 / (200 - 182) x (200 -140) = 20997
    50392 / 8 / (200 - 181) x (200 -140) = 19892

Seagate has been doing this for many years, but I hadn't noticed that WD's drives had also gone down this path.

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 Post subject: Re: 20,000 reallocations and drive is still serviceable?
PostPosted: October 12th, 2021, 8:02 
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Quote:
has racked up 50,392 reallocations (= 6299 physical sectors)


Is that how this works with 4k sectors? I didn't know this.

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 Post subject: Re: 20,000 reallocations and drive is still serviceable?
PostPosted: October 12th, 2021, 12:03 
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Arch Stanton wrote:
Quote:
has racked up 50,392 reallocations (= 6299 physical sectors)


Is that how this works with 4k sectors? I didn't know this.

I assumed so, but now I see that the pending sector count is 10 which is not a multiple of 8. :-?

The drive in the following thread does seem to fit my assumption, though:

https://forum.hddguru.com/viewtopic.php?f=1&t=41771

This WD40NDZW SMART report suggests that attributes #5 and #196 count logical sectors whereas #197 counts physical sectors:

https://bbs.archlinux.org/viewtopic.php?id=260538

Code:
Device Model:     WDC WD40NDZW-11MR8S1

  5 Reallocated_Sector_Ct   0x0033   198   198   140    Pre-fail  Always       -       304
196 Reallocated_Event_Count 0x0032   001   001   000    Old_age   Always       -       304
197 Current_Pending_Sector  0x0032   199   199   000    Old_age   Always       -       883

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 Post subject: Re: 20,000 reallocations and drive is still serviceable?
PostPosted: October 12th, 2021, 13:35 
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Joined: May 13th, 2019, 7:50
Posts: 446
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fzabkar wrote:
Arch Stanton wrote:
Quote:
has racked up 50,392 reallocations (= 6299 physical sectors)


Is that how this works with 4k sectors? I didn't know this.

I assumed so, but now I see that the pending sector count is 10 which is not a multiple of 8. :-?

The drive in the following thread does seem to fit my assumption, though:

https://forum.hddguru.com/viewtopic.php?f=1&t=41771

This WD40NDZW SMART report suggests that attributes #5 and #196 count logical sectors whereas #197 counts physical sectors:

https://bbs.archlinux.org/viewtopic.php?id=260538

Code:
Device Model:     WDC WD40NDZW-11MR8S1

  5 Reallocated_Sector_Ct   0x0033   198   198   140    Pre-fail  Always       -       304
196 Reallocated_Event_Count 0x0032   001   001   000    Old_age   Always       -       304
197 Current_Pending_Sector  0x0032   199   199   000    Old_age   Always       -       883


I have always wondered about 'event count' too. What does it actually count. Can it do multiple sectors in one 'event' and would it count it as one event? reason I wondered was seeing different numbers for reallocated and reallocation events.

TBH I have never actually seen the format in which sector reallocation are kept. I'm sure you know Frank, can it reallocate a range and then log it as one event?

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 Post subject: Re: 20,000 reallocations and drive is still serviceable?
PostPosted: October 12th, 2021, 14:39 
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Arch Stanton wrote:
TBH I have never actually seen the format in which sector reallocation are kept. I'm sure you know Frank, can it reallocate a range and then log it as one event?

I don't know, either.

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