On Thu, 14 Apr 2011 18:11:59 +1000 NeilBrown <neilb@xxxxxxx> wrote: > On Thu, 14 Apr 2011 11:57:47 +0400 CoolCold <coolthecold@xxxxxxxxx> wrote: > > > Just my 2 cents: I've faced problems when newer disk was smaller than > > old disk two or three times, so using partitions now with setting some > > free space at the end - something near 80 or 100 megabytes. There are also some Gigabyte motherboards which like to cut off a small portion of a disk at the end via HPA, and writing a backup of their BIOS there. https://encrypted.google.com/search?q=gigabyte+bios+hpa If you had your user data or mdadm metadata there, bad luck. On earlier motherboards this was done automatically to every new disk on SATA0, on newer ones I think it's optional and can be disabled. But anyway, I now prefer to leave about 8 MB of space at the end of each drive unpartitioned, just in case. And another point, again related to buggy BIOSes: some of them seem to read first sectors of all attached disks and expect to see an MBR-style partition table there; and if there's something else instead (e.g. basically random data, in case of the whole disk used for RAID), they may become confused and lock-up at boot. I had a couple of such cases where a board would lock-up at HDD detection with a certain drive attached, and would only boot up properly after it was zeroed and repartitioned. > > You don't need partitions to do this. Just use the --size option to mdadm. But then the 1.x+ metadata is still stored at the very end of the device, which makes it vulnerable to the HPA problem described above. -- With respect, Roman
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