Talk:Self-Monitoring, Analysis, and Reporting Technology
From Wikipedia, the free encyclopedia
Contents |
[edit] SMART Attributes List
Some descriptions of the SMART attributes are clearly incorrect. "Load" refers to the operation and number of times the heads move from parked to unparked, not when the drive is seeking. GMR head amplitude refers to the signal from the read head, not any movement. "Read Channel Margin" description is content-free.
[edit] Reallocated sectors
Please make it easier for me to **use** this information. Please enhance the Table entries.
Could we get practical and say, This is a down-counter, and, when zero, there is no way to deal with additional sectors whose read errors are too severe to be fixed with Error Correction Codes.
In the discussion above the Table, tell me, if there is no more space to absorb a sector needing reallocation, does my drive now pass errors up to the opsys file system, which reports read errors and/or other file unavailability?
In the table, you can make room by erasing: "the more sectors that are reallocated, the more read/write speed will decrease". This is true. However, it hardly matters to a user who is suffering data loss, possible data corruption, and potential boot failure, which blocks access to everything.
My SMARTCTRL under WinXP or Knoppix shows
Reallocated_Sector_Ct
VALUE 1
WORST 1
THRESHOLD 63 (Please confirm that a number less than 63 is bad -- but which number?)
This "pre-failure" category of parameter is UPDATED "always".
WHEN_FAILED is "FAILING_NOW". How can I tell? Because VALUE 1 is less than THRESHOLD 63?
The "RA" column (I do not know what this is. Do you? RAW counts?) is 12. 12 is not 1 and 12 is not 63. I wonder what 12 is.
This page has not yet evolved into a pratical guide and it still lacks an accessible exposition of the topic's salient points. Nevertheless, and IMHO, it is already far ahead of most pages and posts on the Internet. So let's not stop now ! Jerry-va 01:27, 29 May 2006 (UTC)jerry-va
- The final column is RAW_VALUE, and 12 for the Reallocated_Sector_Ct attribute means that 12 bad sectors have been remapped. You should replace this disk soon, as that number will only rise, and the higher it gets, the more data you're going to lose. --Error28 12:03, 4 September 2006 (UTC)
[edit] Temperature sensor
the section on temperature and temperature sensors is opiniated and somewhat incorrect / not up to date. all the hard drives from 1998+ include a temperature sensor. the reason: all modern hard drives use GMR heads (Giant Magneto Resistive heads), which requires very accurate temperature measurement to be able to read the data back (the difference between a 0 and a 1 readback is about the same order of magnitude as a 0.1 degrees Celsius change in the GMR head).
also, the temperature failure mode is not necessarily cumulative.
[edit] Curious sentence
<partsunkn> SMART is a system used to kill the drive when the warranty is up —Clarknova 03:35, 28 February 2006 (UTC)
Removed the following curious sentence from "working modality".
- Manufacturing companies which claim to support S.M.A.R.T. but withhold specific sensor information on individual products include Seagate, [...]
[...], indeed! What the frip. - 194.89.3.244 17:56, 28 February 2006 (UTC)
[edit] Read Error Rate description incorrect
Elsewhere I have read that a high value for Read Error Rate is good, and the attribute value decreases as read error rate increase.
Consistent with this, the two SMART monitoring tools I have used alert the user when the Read Error Rate attribute value falls below a threshold.
This description deserves accuracy and careful explanation perhaps more than any other, since this attribute is so critical.
-- I think it means 'time between read errors'; the smaller the number, the higher the rate, but whether it's seconds, hours, or fortnights, I couldn't begin to guess.
[edit] Frustration with SMART
I'd like it if the table spelled out what the "good" and "bad" values of the attributes are.
- The general rule is that higher is better than lower, except in the case of temperature. The specific thresholds of "OK" and "failing" are up to the manufacturers to specify. Most of the numbers involved are arbitrary and defined separately by the manufacturers. GreenReaper 16:07, 24 August 2006 (UTC)
[edit] More frustration...
I also feel that nobody tells you some useful (average, maybe IQ 100, no IT degree) human-readable information about your harddisk. Something like "your harddisk /dev/hda is 2.8 years old the probability that it will survive this month is 98% (suggested replacement value: 96%; suggested backup value: 99%)". But I'm confused by 1000 different values. How bad are they really? Where should the values be (see comment above)? It does not really help to make a business decision to replace or not to replace the drive. Can someone please shed some light into this? Can smartmontools developer please think of the CTO's business decision of replacing or not replacing a disk? And some useful information for the home user. THANKS -- Michael Janich 09:15, 31 July 2006 (UTC)
- Most hard disk fail within the first two years, if it doesn't fail the within those years, it is a good idea to keep the hard disk for another 3 years.
If you can plot the failure rate of hard disk, it starts off very high, then it goes to its lowest point around two years, and then slowly climbs back up to the rate at which it started. Hope that helps Hqduong 08:10, 5 December 2006 (UTC)
- Google published a study on hard disks that claimed (based on memory, not citation) that 1) only half the disks that failed had something significant in their SMART readouts, and 2) only half the disks with something significant in their SMART readings actually failed. So after all the hoopla, it may not be that useful after all. --Alvestrand 07:39, 19 March 2007 (UTC)
[edit] SMART and RAID
Any idea if SMART can still be used on HDD's included in a RAID array? --Evolve2k 05:06, 7 January 2007 (UTC)
-
- I have seen some motherboards with hardware RAID support/PCI RAID expansion cards that have a BIOS/firmware capable of retrieving and displaying SMART data. No idea if there's anything out there that lets you do this in software though. SMART is a very mysterious technology IMO. --86.138.51.21 08:20, 26 January 2007 (UTC)
[edit] Merging in Threshold Exceeds Condition
Since the mergeto tag of the Threshold Exceeds Condition article says to discuss the subject here:
- Merge. My opinion. --Alvestrand 22:16, 13 January 2007 (UTC)
