DigitalDivide Posted October 20, 2011 Share Posted October 20, 2011 Hi, I just bought a new Hitachi 2TB 5K300 drive and want to pop it into my server. I'm just not sure if with versions 4.7 if I still need to run a preclear on it. I added the drive and see it in the Devices tab and assigned to a slot. It's listed as SDE. On the Main page it tells me it found 1 new drive. If I click start it will clear it and make it available to the array. Is that the same as the preclear? It's been so long and so many changes I'm lost. Quote Link to comment
Rajahal Posted October 20, 2011 Share Posted October 20, 2011 No, that is not the same as preclear. Preclear is not part of the stock distribution of unRAID. Preclear must be manually installed and run (see the preclear thread for details). Preclear is optional but highly recommended, especially as you are using a new disk and you don't yet know if it is trustworthy. Preclear will not only thoroughly test the disk for mechanical problems, but it will also clear it allowing unRAID to add it to the array in a matter of minutes (all unRAID has to do is format the disk). The preclear cycle itself will take a long time. Average length for a 2TB disk is 35 hours. If you choose not to preclear the drive, then unRAID will clear it for you. The drive will not be tested for mechanical problems, and your array will be down during the entire clearing process (which will take about 10 hours for a 2TB drive). Quote Link to comment
DigitalDivide Posted October 20, 2011 Author Share Posted October 20, 2011 Hi Raj, thanks! Just to confirm for the Hitachi drive I want 4K aligned set in the settings tab for drives correct? Quote Link to comment
Johnm Posted October 21, 2011 Share Posted October 21, 2011 If i recall correctly. the Hitachi is not a 4k drive. BUT, for all 2TB drives in 4.7 (and newer) you should go ahead and use the -A flag to run it as 4K aligned. the only exception to this is a jumpered 2TB WD EARS drive. Edit: I guess I should say, it does not hurt to run a 512k drive as 4k aligned, it does hurt to run it the other way around. Quote Link to comment
DigitalDivide Posted October 21, 2011 Author Share Posted October 21, 2011 Well I didn't use the -A flag but in the settings for 4.7 for default partition size I have it set at MBR 4K Aligned. From what I understood when running the preclear it uses what I have the default partition size set at. Do I have this correct? I have a mix of drives on my system with some of them being EARS drives which are jumpered. So I guess my question is am I good to go or do I have to change something? Quote Link to comment
Johnm Posted October 21, 2011 Share Posted October 21, 2011 Well I didn't use the -A flag but in the settings for 4.7 for default partition size I have it set at MBR 4K Aligned. From what I understood when running the preclear it uses what I have the default partition size set at. Do I have this correct? I have a mix of drives on my system with some of them being EARS drives which are jumpered. So I guess my question is am I good to go or do I have to change something? that is correct. if your default is set to 4K and you used no flag, it used 4K partitioning. the same as if yo used -A Quote Link to comment
DigitalDivide Posted October 22, 2011 Author Share Posted October 22, 2011 THanks! Quote Link to comment
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