On 02/10/12 01:35, Stephen Thompson wrote:
>
>
> Correction, the non-problem drive has a higher "ECC fast" error count,
> but the problem drive has a significantly higher "Corrective algorithm
> invocations" count.
>
What that means is that it rewrote the data, which accounts for the
lower throughput.
LTO drives read as they write and if there are errors, they write again.
If a cleaning tape doesn't work then you need to get the drive looked
at/replaced under warranty.
> On 10/1/12 5:33 PM, Stephen Thompson wrote:
>>
>> On 10/1/12 4:06 PM, Alan Brown wrote:
>>> On 01/10/12 23:38, Stephen Thompson wrote:
>>>> More importantly, I realized that my testing 6 months ago was not on
>>>> all 4 of my drives, but only 2 of them. Today, I discovered one of my
>>>> drives (untested in the past) is getting 1/2 the throughput for random
>>>> data writes as the others!!
>>> "smartctl -a /dev/sg(drive)" will tell you a lot
>>>
>>> Put a cleaning tape in it....
>>>
>>>
>>>
>>>
>>>
>>
>> Cleaning tape did not improve results.
>>
>> I see some errors in the counter log on the problem drive, but I see
>> even more errors on another drive which isn't having a throughput
>> problem (specifically SL500 Drive 1 is the lower throughput, but C4
>> Drive 1 actually has a higher error count).
>>
>>
>>
>> SL500 Drive 0 (~60MB/s random data throughput)
>> =============
>> Error counter log:
>> Errors Corrected by Total Correction
>> Gigabytes Total
>> ECC rereads/ errors algorithm
>> processed uncorrected
>> fast | delayed rewrites corrected invocations [10^9
>> bytes] errors
>> read: 0 0 0 0 0 0.000
>> 0
>> write: 0 0 0 0 0 0.000
>> 0
>>
>>
>> SL500 Drive 1 (~30MB/s random data throughput)
>> =============
>> Error counter log:
>> Errors Corrected by Total Correction
>> Gigabytes Total
>> ECC rereads/ errors algorithm
>> processed uncorrected
>> fast | delayed rewrites corrected invocations [10^9
>> bytes] errors
>> read: 0 0 0 0 0 0.000
>> 0
>> write: 10454 0 0 0 821389 0.000
>> 0
>>
>>
>> C4 Drive 0 (~60MB/s random data throughput)
>> ==========
>> Error counter log:
>> Errors Corrected by Total Correction
>> Gigabytes Total
>> ECC rereads/ errors algorithm
>> processed uncorrected
>> fast | delayed rewrites corrected invocations [10^9
>> bytes] errors
>> read: 2 0 0 0 2 0.000
>> 0
>> write: 0 0 0 0 0 0.000
>> 0
>>
>>
>> C4 Drive 1 (~60MB/s random data throughput)
>> ==========
>> Error counter log:
>> Errors Corrected by Total Correction
>> Gigabytes Total
>> ECC rereads/ errors algorithm
>> processed uncorrected
>> fast | delayed rewrites corrected invocations [10^9
>> bytes] errors
>> read: 2 0 0 0 2 0.000
>> 0
>> write: 18961 0 0 0 48261 0.000
>> 0
>>
>>
>>
>>
>> Stephen
>>
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