Path: csiph.com!news.mixmin.net!eternal-september.org!feeder.eternal-september.org!mx02.eternal-september.org!.POSTED!not-for-mail From: Daniel James Newsgroups: comp.sys.ibm.pc.hardware.storage,uk.comp.homebuilt Subject: Re: Cannot access new Seagate external HD Date: Fri, 11 Sep 2015 15:17:23 +0100 Organization: A noiseless patient Spider Lines: 41 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Injection-Info: mx02.eternal-september.org; posting-host="e16147c885e59d133f2ef7d44168f0c1"; logging-data="13351"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX19VhTrFhUPKChK1QP3Eq9pr" X-Newsreader: Virtual Access Open Source http://www.virtual-access.org/ Cancel-Lock: sha1:EwHaXbcxR34QpSECcSMvNGCF+NU= Xref: csiph.com comp.sys.ibm.pc.hardware.storage:6408 uk.comp.homebuilt:40292 In article , Terry Pinnell wrote: > And anyway, I later found that MBR can 'only support drives under 2 > TB'. That's not absolutely correct. If you want the whole story, MBR can only support drives that have 2^32 or fewer blocks, and as a block is traditionally 512 bytes that means the biggest disk you can have is 2TB. .. or, strictly, that you can use a bigger disk but only put partitions on the first 2TB of it. But, if you're using an OS that can work with disks whose blocks are bigger than 512 bytes you can use all of a bigger disk and still use MBR. [Note that although a lot of modern disks internally use a 4k physical sector, they typically then pretend that the sectors are only 512 bytes, so that's what the OS sees ... and you're back to the 2TB limit.] The 512-byte sector size is so pathologically hard-coded into Windows that you can't change it. Linux can support different physical sector sizes, so you could probably make MBR work on a large disk, but I wouldn't expect all disk management tools to run correctly because that 512 byte value must be (erroneously) baked into an awful lot of sourcecode. However, the disks you've purchased are not bigger than 2TB, so MBR will handle them just fine. It's just that they've been pre-partitioned with GPT. You only have to wipe them and repartition. Note that under the GPT scheme there is a boot record at the start of the disk (as usual) and also a backup copy of the partition table at the far end of the disk. UEFI firmware may refuse to allow you to use the disk as MBR while either of those exists, so you need to wipe both of them before repartitioning the disk as MBR. -- Cheers, Daniel.