Hi Tudor. All disks I have report the same size, even though they are different brand/model #fdisk -l | grep Disk Disk /dev/sdc: 2000.4 GB, 2000398934016 bytes Disk /dev/sdd: 2000.4 GB, 2000398934016 bytes Disk /dev/sde: 2000.4 GB, 2000398934016 bytes Disk /dev/sdf: 2000.4 GB, 2000398934016 bytes Disk /dev/sdg: 2000.4 GB, 2000398934016 bytes They are 2 WD RED (WDC WD20EFRX-68AX9N0), 1 WD GREEN (WDC WD20EARX-00PASB0) and 2 SAMSUNG (HD204UI). If the 2 WD RED bahave as they should I might buy some more as soon as the others fail, otherwise I will try something different (that's why I want to keep the system as flexible as possible). The 2 samsung SMART infos are already "screaming for help" and, actually, a third Samsung already failed last year. Terrible drives, terrible support from Samsung that replaced the drive (still under warranty) with a refurbished one that failed within 10 days from arrival. Anyway, regarding how much free space to leave, another user suggested 2-10 MB should be sufficient. Thanks for your infos. Andrea On Mon, May 27, 2013 at 4:36 AM, Tudor Holton <tudor@xxxxxxxxxxxxxxxxx> wrote: > Hi Andrea, > > I noticed your question wasn't answered, so I'll give it a shot. Bear in > mind that I'm relatively new here, so take everything I say with a pinch > of > salt. :-) > > At some point in the past, manufacturers of hard disks released disks with > the same "marketing" size but different actual capacities. For example, > instead of 1TB being a 1 Tebibyte 2^40 (1,099,511,627,776 bytes), they > sold > lower capacity drives by using a different base. 1TB could be 1000GB > (10^3*2^30 = 1,073,741,824,000 bytes), 1024GB (2^10*10^9 = > 1,024,000,000,000 > bytes) or even a "true" Terabyte at 10^12 bytes (1,000,000,000,000 bytes). > If we were swapping brands, and moved from a 2^40 to a 10^12 model, then > our > array wouldn't fit anymore. :-( > > These days, things are a bit clearer as people understand the differences > between the Terabytes and Tebibytes. > > Thankfully, most modern disk sizes are standardised, but still with some > small variances. It would be wise to look at the drives you have > purchased > and look at the actual storage capacity then take the lowest one and use > that. You may want to add in some additional buffer, also, just in case. > > I hope that helps you make your decision. :-) > > Cheers, > Tudor. > > > On 24/05/13 19:25, Andrea Bolandrina wrote: >> >> Hi All, >> >> In choosing the right size for a mdadm array the manual sais: >> "Sometimes a replacement drive can be a little smaller than the >> original drives though this should be minimised by IDEMA standards. >> Such a replacement drive will be rejected by md. >> To guard against this it can be useful to set the initial size >> slightly smaller than the smaller device with the aim that it will >> still be larger than any replacement." >> >> I want to do a 5x2TB md (raid 6) array . >> Could you advise me how "slightly smaller" should my partitions be? >> >> 100MB smaller than the actual size? 1GB? >> >> Thank in advance for the attention. >> >> Regards, >> Andrea >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-raid" in >> the body of a message to majordomo@xxxxxxxxxxxxxxx >> More majordomo info at http://vger.kernel.org/majordomo-info.html > > -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
