|From:||"Martin K. Petersen" <martin.petersen-AT-oracle.com>|
|To:||James Bottomley <James.Bottomley-AT-suse.de>|
|Subject:||Re: ATA 4 KiB sector issues.|
|Date:||Mon, 08 Mar 2010 10:33:00 -0500|
|Cc:||Tejun Heo <tj-AT-kernel.org>, "linux-ide-AT-vger.kernel.org" <linux-ide-AT-vger.kernel.org>, lkml <linux-kernel-AT-vger.kernel.org>, Daniel Taylor <Daniel.Taylor-AT-wdc.com>, Jeff Garzik <jeff-AT-garzik.org>, Mark Lord <kernel-AT-teksavvy.com>, tytso-AT-mit.edu, "H. Peter Anvin" <hpa-AT-zytor.com>, hirofumi-AT-mail.parknet.co.jp, Andrew Morton <akpm-AT-linux-foundation.org>, Alan Cox <alan-AT-lxorguk.ukuu.org.uk>, irtiger-AT-gmail.com, Matthew Wilcox <matthew-AT-wil.cx>, aschnell-AT-suse.de, knikanth-AT-suse.de, jdelvare-AT-suse.de|
>>>>> "James" == James Bottomley <James.Bottomley@suse.de> writes: James> However, for 4k sectors, the main issues which have shown up in James> testing by others (mostly Martin) are James> 1. In native 4k mode, we work perfectly fine. *however*, James> most BIOSs can't boot native 4k drives. Correct. I have engaged with pretty much all the big OEMs in the industry and so far the interest has been near zero. James> 4. The aligment problem is made more complex by drives that James> make use of the offset exponent feature (what you refer James> to as offset by one) ... fortunately very few of these James> have been seen in the wild and we're hopeful they can be James> shot before they breed. This topic is constantly up for debate in IDEMA. However, it looks like we might win because of the impending demise of XP. James> so the bottom line seems to be that if you want the device as a James> non boot disk, use native 4k sectors and a non-msdos partition James> label. If you want to boot from the drive and your bios won't James> book 4k natively, partition everything using the 512 emulation James> and try to align the partitions correctly. If your bios/uefi James> will boot 4k natively, just use it and whatever partition label James> the bios/uefi supports. James> Martin can fill in the pieces I've left out. Here's my latest take given what I hear on the grapevine: 1. 512-byte logical block size drives will be around forever for legacy deployments because nobody is willing to do the required BIOS int13 work. It's not just a BIOS thing, this requires heavy changes to HBA boot ROMs as well. 2. Some vendors are working on EFI firmware and will support booting off of 4KB LBS drives there. This is mostly aimed at the server space. 3. 4 KB logical block size drives will mainly be targeted for use inside arrays. Off the shelf enterprise drive models will most likely continue to ship with a 512-byte LBS. 4. Part of the hesitation to work on booting off of 4 KB lbs drives is motivated by a general trend in the industry to move boot functionality to SSD. There are 4 KB LBS SSDs out there but in general the industry is sticking to ATA for local boot. -- Martin K. Petersen Oracle Linux Engineering
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