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From: Franc Zabkar on 25 Jan 2010 18:39 On 22 Jan 2010 09:43:07 GMT, Arno <me(a)privacy.net> put finger to keyboard and composed: >Well, I think I still do not undertsand the seek error rate attribute, Here are two examples for two Seagate ST3500630AS drives: ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE 7 Seek_Error_Rate 0x000f 035 024 030 Pre-fail Always In_the_past 54443054162961 7 Seek_Error_Rate 0x000f 059 048 030 Pre-fail Always - 1507770244954 Convert the raw decimal attribute values to hex: 54443054162961 = 0x318402e76411 (drive A) 1507770244954 = 0x015f0e1c1f5a (drive B) AIUI, the number of seek errors is stored in the uppermost 16 bits of the 48-bit attribute value, and the total number of seeks is stored in the lower 32 bits. So for drive A, # seek errors = 0x3184 # total seeks = 0x02e76411 The normalised attribute value is logarithmic and appears to be calculated as follows: Normalised value = -10 log (seek errors/total seeks) If the number of seek errors is 0, then use a value of 1. For drive A, this works out as ... -10 x log(0x3184 / 0x02e76411) = 35.8471493 For drive B it is ... -10 x log(0x015f / 0x0e1c1f5a) = 58.2893528 Not exactly right, but very close ... The worst case value of 24 corresponds to an error rate of ... -10 ^ 2.4 = 1/251 .... ie one error in every 250 seeks. - Franc Zabkar -- Please remove one 'i' from my address when replying by email.
From: Franc Zabkar on 25 Jan 2010 18:55 On Tue, 26 Jan 2010 10:39:03 +1100, Franc Zabkar <fzabkar(a)iinternode.on.net> put finger to keyboard and composed: >The worst case value of 24 corresponds to an error rate of ... > > -10 ^ 2.4 = 1/251 Sorry, that should be ... 10 ^ (-2.4) - Franc Zabkar -- Please remove one 'i' from my address when replying by email.
From: Arno on 26 Jan 2010 00:23
In comp.sys.ibm.pc.hardware.storage Franc Zabkar <fzabkar(a)iinternode.on.net> wrote: > On Tue, 26 Jan 2010 10:39:03 +1100, Franc Zabkar > <fzabkar(a)iinternode.on.net> put finger to keyboard and composed: >>The worst case value of 24 corresponds to an error rate of ... >> >> -10 ^ 2.4 = 1/251 > Sorry, that should be ... > 10 ^ (-2.4) > - Franc Zabkar > -- > Please remove one 'i' from my address when replying by email. Thanks, noted and archived in my doc collocetion. Arno -- Arno Wagner, Dr. sc. techn., Dipl. Inform., CISSP -- Email: arno(a)wagner.name GnuPG: ID: 1E25338F FP: 0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F ---- Cuddly UI's are the manifestation of wishful thinking. -- Dylan Evans |