-----Original Message----- From: Tejun Heo [mailto:tj@xxxxxxxxxx] Sent: Monday, March 08, 2010 6:34 PM To: Karel Zak Cc: Martin K. Petersen; linux-ide@xxxxxxxxxxxxxxx; lkml; Daniel Taylor; Jeff Garzik; Mark Lord; tytso@xxxxxxx; H. Peter Anvin; hirofumi@xxxxxxxxxxxxxxxxxx; Andrew Morton; Alan Cox; irtiger@xxxxxxxxx; Matthew Wilcox; aschnell@xxxxxxx; knikanth@xxxxxxx; jdelvare@xxxxxxx; Jim Meyering Subject: Re: ATA 4 KiB sector issues. Hello, On 03/09/2010 04:58 AM, Karel Zak wrote: >> Tejun> Reportedly, commonly used partitioners aren't ready to handle >> Tejun> drives larger than 2 TiB in any configuration and alignment >> Tejun> isn't > > The limit is specific for DOS partition table (with 512-byte log. > sectors), but for example GPT uses 64-bit LBA. I believe that our > partitioning tools don't introduce any other restriction. Hmmm... the 'reportedly' was from Daniel Taylor or maybe I just misinterpreted the conversation. Daniel, can you please fill in? DLT> The problem that I see is that the installers and upper level applications do not make good choices for partition layout. DLT> "parted", itself, seems to work OK in the latest version. One of the things I've heard since I started this process is that DLT> there are some libraries associated with the process of partitioning/formatting. Perhaps the upper layers and those DLT> libraries aren't synced up? >> Tejun> done properly for drives with 4 KiB physical sectors. 4 KiB >> Tejun> logical sector support is broken in both the kernel >> >> Huh, what? My homedir is on a 4KiB LBS/PBS drive and has been for ~2 >> years. By default, they aren't aligned properly, are they? >> Tejun> (need more details and probably a whole section on partitioner >> Tejun> behaviors) >> >> I'm Cc:'ing Karel Zak and Jim Meyering who have been doing all the >> alignment work for fdisk and parted respectively. Karel, Jim: The >> full writeup is here: >> >> http://ata.wiki.kernel.org/index.php/ATA_4_KiB_sector_issues >> >> It'd be great if you guys could share what you have been doing to the >> tooling. > > small summary: > > - libblkid provides unified API to topology information, it supports: > - ioctls (kernel >= 2.6.32) > - sysfs (kernel >= 2.6.31) > - stripe chunk size and stripe width for DM, MD. LVM and evms on > old kernels > - libparted and fdisk are linked against libblkid > > - fdisk supports 4KiB logical sector size (util-linux-ng >= 2.15 > - fdisk supports 4KiB physical sector size (util-linux-ng >= 2.17) > - fdisk uses 1MiB alignment (or more if optimal I/O size is bigger) > and alignment_offset for all partitions in non-DOS mode > (util-linux-ng >= 2.17.1) That's great. Daniel, maybe you were testing older versions? Or maybe those failures were manifested from libata mishandling 4KiB r/w requets. DLT> As I said, above, it could be libraries. I was not aware that so much of the implementation was embedded there. > - parted supports 4KiB physical sector size > - parted uses 1MiB alignment for disks with unknown topology, disks > with topology information are aligned to optimal (or minimum) I/O > size (parted >= 2.1) This will result in incorrect alignment for drives which lie about the physical sector size to work around BIOS/drivers issues (C-1). It would probably be best to align to at least 1MiB. DLT> Please. > - EFI GPT code in the kernel has been updated to works properly with > 4KiB sectors (kernel >= 2.6.33) libata is broken for logical 4KiB ATA devices tho. I'll fix it up. > - mkfs.{ext,xfs,gfs2,ocfs2} have been update to work properly with > topology information, mkfs.{ext,xfs} are linked against libblkid > for compatibility with old kernel (for stripe chunk size / width) > > - Fedora-13/RHEL6 installer uses libparted with 4KiB support > > - alignment_offset & 4KiB support is planned for LUKS (cryptsetup) > >> Tejun> Unfortunately, the transition to 4 KiB sector size, physical >> Tejun> only or logical too, is looking fairly ugly. Hopefully, a >> Tejun> reasonable solution can be reached in not too distant future >> Tejun> but even with all the software side updated, it looks like >> Tejun> it's gonna cause significant amount of confusion and frustration. >> >> With regards to XP compatibility I don't think we should go too much >> out of our way to accommodate it. XP has been disowned by its master >> and I think virtualization will take care of the rest. Yeah, good point. I'm just a bit worried that it might generate a lot of frustrated bug reports. Well, maybe we should just advise users to install windows first and then install Linux. DLT> Simple reality is that XP is "forever". Drives >2TiB, which may be USB-attached, used with XP will be MBR-partitioned DLT> and use 4096-byte sectors. We need to be able to read/write those disks on Linux systems. >> FWIW, recent fdisk has a command line flag that will enable/disable >> DOS compatible layout. > > yes, util-linux-ng 2.17.1, fdisk -c > > Note that non-DOS mode will be default in the next major > util-linux-ng release. I'll try to merge these information into the ata-4k doc. Thank you very much. DLT> One last comment: I just tried to partition and format a >2TiB drive on fully updated Ubuntu 9.10 with GParted. DLT> I selected not to cylinder align, use GPT and ext3, and to put 1 MiB preceeding and following. libparted failed DLT> with "unable to satisfy all constraints of the partition". Using "parted", I created the partition, and then DLT> GParted was able to apply the ext3 file system. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
