The NSS326 hardware is based from QNAP's model TS-659 Pro+ and the tested HHD list is available from QNAP website: http://www.qnap.com/USEng/pro_compatibility.asp I would recommend to stick with the HHD already tested/qualified so if in the future you have an issue with HHD. It would be better for technical personel to help.
I am a little confused beacuse that list is different to the Cisco approved disk drive list. Specifically the WD Green series. I also see many people using / selling the 326 with the Green series. Qnap says the green series should never be used, but the cisco list has them as approved ?
Cisco has 3 models in the market and these are based from QNAP's TSx59 Pro+ hardware. QNAP and Cisco had different way to qualified a drive and recommend for user to use. For Cisco, each of the hard drive model from the approved list was actually tested to making sure the reliability of the drive installed in the NSS. There are number of drive models in the WD's Green series did not make to the AVL. So if you see a drive model in the Cisco AVL, it had been tested and I would recommend to get that model to use with the NSS. If the model you purchased and it is not on the AVL list, it was either failed to make the list. Unfortunately, Cisco existed the Storage market for SMB market since summer of last year so the drive qualification was also stopped. The only source for new model, in your case, is come from QNAP. However, if you are purched Cisco NSS hardware, you have 5 years hardware warranty from the date of purchased. Any software issue will be handled by QNAP (ex-partner).
Note: Cisco also worked very closely with WD team in the past to resolved any issue found on their drives during the testing. The confidentl level to use models from Cisco AVL list is much higher due to the test done in Cisco's lab.
In summary, only drive model that is working in the NSS hardware (passed life expectation tests, stress tests, performance tests, RAIDs, etc..) is made to the AVL list, any model was not amke to the list--it is not recommended.
As for QNAP's AVL, while the base system are the same between TS-x59 Pro+ and the NSS32x. The QNAP's AVL list is impressed but you need to pay attention to the notes from their web site--on the right side (very important) . The note indicated things that was not went well or things customer needs to be aware of before select the drive model.
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