Please help me to understand the SMART attributes

[kit17]

I have 2 Toshiba 4TB HDDs (same model, different serial numbers), used for 2-3 years and 5 months respectively.

 

The 2-3 years one:

 

The 5 months one:

 

What is the the difference between "Value" and "Raw Value"?

The "Values" of the highlighted attributes in the first HDD are same as the second one, but the "Raw Values" are different, why would this happen?

 

Does "Value" mean the current value? I see most of them equal to their "Worst".

If yes, does it mean that both two HDDs are doing their worst?

 

And most importantly, how to tell if I should replace the failing HDDs?

Edited March 11, 2018 by kit17

[JorgeB]

UDMA CRC errors indicate a connection problem, usually the SATA cable, if it keeps increasing replace the cable.

 

Reallocated sectors is never a good sign, but since it's just a few and if it remains stable disk is should be OK for now,

[kit17]

1 hour ago, johnnie.black said:

UDMA CRC errors indicate a connection problem, usually the SATA cable, if it keeps increasing replace the cable.

 

Reallocated sectors is never a good sign, but since it's just a few and if it remains stable disk is should be OK for now,

Thank you for the explanation.

 

Can you tell me more about the differences between the values of the two disks?

The values of the same attribute of both disks are same, but why only the first one shows the warning?

 

And most of the values are currently at their worst cases, isn't that a bad sign?

[JorgeB]

12 minutes ago, kit17 said:

The values of the same attribute of both disks are same

You need to look at the raw value for those attributes.

 

13 minutes ago, kit17 said:

And most of the values are currently at their worst cases, isn't that a bad sign?

No, that's normal for most attributes.

 

[kit17]

On 3/12/2018 at 4:45 AM, johnnie.black said:

You need to look at the raw value for those attributes.

Is "Value" meaningless?

[bonienl]

Perhaps this helps https://ma.juii.net/blog/interpret-smart-attributes

[kit17]

On 3/13/2018 at 5:18 AM, bonienl said:

Perhaps this helps https://ma.juii.net/blog/interpret-smart-attributes

Very detailed meanings of the columns

 

Thank you

[kit17]

On 3/12/2018 at 3:16 AM, johnnie.black said:

UDMA CRC errors indicate a connection problem, usually the SATA cable, if it keeps increasing replace the cable.

 

Reallocated sectors is never a good sign, but since it's just a few and if it remains stable disk is should be OK for now,

I have replaced the SATA cables for two disks with "UDMA CRC error count" warning, but the their raw values remain unchanged after rebooting the system.

 

I even swapped one of them with another disk that has no any SMART attribute warning, but still the same.

 

Do I have to wait for a while so that the values will be refreshed? Or can I re-scan the SMART attributes manually?

[Squid]

1 minute ago, kit17 said:

have replaced the SATA cables for two disks with "UDMA CRC error count" warning, but the their raw values remain unchanged after rebooting the system.

That count will never decrease.  If you have notifications enabled, unRaid will let you know when it increases.

[bonienl]

That counter is not reset. As long as it does not increment you are fine.

 

[kit17]

I see, thank you