Boston Linux & UNIX was originally founded in 1994 as part of The Boston Computer Society. We meet on the third Wednesday of each month at the Massachusetts Institute of Technology, in Building E51.

BLU Discuss list archive


[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[Discuss] SSD drives vs. Mechanical drives



On Wed, May 7, 2014 at 12:40 PM, Richard Pieri <richard.pieri at gmail.com> wrote:
> Dan Ritter wrote:
>> 3Ware tw_cli man page:
>>
>>  Verify activity attempts to verify all units based on their unit
>>  type. Verifying RAID-1 involves checking that both drives contain the
>
> It doesn't work reliably. If the data is corrupted somewhere in the
> controller itself (flakey cache for example) then the checksums will be
> correct but the data that is written and checked is wrong. I've had a
> 3Ware controller do this to me. All of the checksums matched up but the
> data was damaged prior to the calculations and writes. Correctly written
> and replicated wrong data is still wrong data. :P

And checksums can be incorrectly generated/verified by any hardware at any time.
I claim that 100% data integrity is impossible.   I don't think even
ZFS can guarantee
100% data integrity with the right set of bizarre hardware failures in
the CPU/RAM of the
computer.  Pointing out that all hardware can have errors is kind of a
moot point.
More important is being able to assess what kinds of hardware/software
failures can result in loss of integrity (or data) and their relative
probabilities.

Bill Bogstad



BLU is a member of BostonUserGroups
BLU is a member of BostonUserGroups
We also thank MIT for the use of their facilities.

Valid HTML 4.01! Valid CSS!



Boston Linux & Unix / webmaster@blu.org