ATA 4 KiB sector issues.
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From: Arnd Bergmann on 9 Mar 2010 18:50 On Monday 08 March 2010 04:48:35 Tejun Heo wrote: > Unfortunately, while Windows can assume that newer releases won't > share the hard drive with older releases including Windows XP, Linux > distros can't do that. There will be many installations where a > modern Linux distros share a hard drive with older releases of > Windows. At this point, I can't see a silver bullet solution. > > Partitioners maybe should only align partitions which will be used by > Linux and default to the traditional layout for others while allowing > explicit override. I think Windows XP wouldn't have problem with > differently aligned partitions as long as it doesn't actually use them > but haven't tested it. Any idea if XP can cope with partition tables that use a 32-sector, 128-head geometry rather than the default 63-sector, 255-head one? That seems to be what some flash memory cards are using and it would make any cylinder aligned partition also 4096-byte aligned, at the cost of moving the 1024-cylinder boundary from 7.88 GiB to 2 GiB. Do we know of anything that requires 63s/255h? Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Tejun Heo on 9 Mar 2010 19:00 Hello, On 03/09/2010 04:27 PM, Jim Meyering wrote: > Related information, prompted by my recent encounter with a > tool that refused to let me use a GPT partition table. > > Partition table formats: prefer GUID/GPT: > > Having spent more than my share of time looking at partition table > formats recently, I am now strongly biased against DOS partition > tables, and for GUID/GPT ones. In addition to allowing for >2GiB > partition offsets and lengths, GPT tables provide for better > protection in case of corruption (checksums, backup table at end > of disk) and don't have the anachronistic distinction of primary > and extended/logical partitions (all partitions are "primary"). > You can even give each partition a name. The only reason to use a > DOS partition table on a new installation is if you're stuck with > a requirement of using an OS like XP on bare metal. > > Please consider encouraging the use of GPT partition tables... > or at least do not *dis*courage their use. I'll surely include it. Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Tejun Heo on 9 Mar 2010 19:10 Hello, On 03/10/2010 07:46 AM, Greg Freemyer wrote: >> As far as partitioning... I believe we should be using GPT partition tables >> where possible. Even on non-EFI systems, it's simply a much better >> partition table format. > > GPT can not be used for boot disks in non-EFI systems, right? IIUC, I think any BIOS should be able to do so as it only cares about the code part of MBR not the partitions and even with GPT the MBR remains the same with the partition part describing the rest of the while disk as a single chunk containing GPT managed area. The only problem is the older operating systems (like XP) which don't understand GPT wouldn't be able to access those partitions. Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Tejun Heo on 9 Mar 2010 19:20 Hello, On 03/09/2010 07:06 PM, Michal Soltys wrote: > Mikael Abrahamsson wrote: >> On Mon, 8 Mar 2010, Tejun Heo wrote: >> >>> http://ata.wiki.kernel.org/index.php/ATA_4_KiB_sector_issues >> >> Excellent summary. >> >>> C-2. Windows XP depends on the traditional partition layout. >> >> Is this really true? WD ships their EARS drives with an alignment tool >> that as far as I can understand, moves the partition so >> it's aligned to 4KiB: Hmmm... I based that claim on the MS KB page and as you pointed out the problem there could probably be issues with specific BIOS implementation interacting badly. I'll update the doc. > XP SP2 (or later) can boot from any place, including logical partitions > (tested that recently). Most important thing is "hidden sectors" (recent > chain.c32 can set that automatically through ntldr and/or sethidden > options). No idea about pre-SP2 ; Win 2000 will not boot from > "misaligned" (with reference to cylinder boundary) partition. I was thinking about testing XP booting this weekend but really want to avoid it, so thanks a lot for the info. I'll update the doc accordingly but can you please enlighten me on how it works and what's broken in detail? So, XP should be fine with any alignment? Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Tejun Heo on 9 Mar 2010 19:30
On 03/10/2010 08:46 AM, Arnd Bergmann wrote: > On Monday 08 March 2010 04:48:35 Tejun Heo wrote: >> Unfortunately, while Windows can assume that newer releases won't >> share the hard drive with older releases including Windows XP, Linux >> distros can't do that. There will be many installations where a >> modern Linux distros share a hard drive with older releases of >> Windows. At this point, I can't see a silver bullet solution. >> >> Partitioners maybe should only align partitions which will be used by >> Linux and default to the traditional layout for others while allowing >> explicit override. I think Windows XP wouldn't have problem with >> differently aligned partitions as long as it doesn't actually use them >> but haven't tested it. > > Any idea if XP can cope with partition tables that use a 32-sector, 128-head > geometry rather than the default 63-sector, 255-head one? That seems to > be what some flash memory cards are using and it would make any cylinder > aligned partition also 4096-byte aligned, at the cost of moving the > 1024-cylinder boundary from 7.88 GiB to 2 GiB. > > Do we know of anything that requires 63s/255h? Michal Soltys pointed out that XP doesn't really depend on the legacy layout although 2000 does (can't boot), so I guess it shouldn't be much of a problem. Regarding the gemetry, IIUC changing it isn't meaningful for compatibility. Geometry information is obtained using a BIOS call (the int Xh thing) and the hard disk itself doesn't carry that information , so unless you go into the BIOS set up and enter those values manually (and I don't think you can do that on many BIOSs these days), there's no way for anyone else to know custom geometry other than solving equations using the CHS and LBA information in the partition table. So, feeding custom geometry to a partitioner which uses CHS to determine the layout is useful to make it create partitions aligned in certain way but as the information regarding the geometry is not recorded anywhere, others will just keep using whatever they were using (255*63) and figure that CHS and LBA in the partition tables just don't match. Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |