Date: Mon, 23 Sep 2013 08:04:19 -0700 From: Ravi Pokala <rp_freebsd@mac.com> To: Rozhuk.IM@gmail.com, 'Jia-Shiun Li' <jiashiun@gmail.com> Cc: freebsd-hackers@freebsd.org, freebsd-hardware@freebsd.org Subject: Re: What's the state of AF-4Kn support? Message-ID: <CE65A521.F453B%rpokala@mac.com> In-Reply-To: <523ff852.4ee8cc0a.44b6.ffffacba@mx.google.com>
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-----Original Message----- From: <rozhuk.im@gmail.com> Reply-To: <Rozhuk.IM@gmail.com> Date: Monday, September 23, 2013 1:13 AM To: 'Jia-Shiun Li' <jiashiun@gmail.com>, Ravi Pokala <rp_freebsd@mac.com> Cc: <freebsd-hackers@freebsd.org>, <freebsd-hardware@freebsd.org> Subject: RE: What's the state of AF-4Kn support? ># install >gpart create -s GPT ada1 >gpart show >gpart add -i 1 -t freebsd-boot -b 40 -s 512 ada1 >gpart add -i 2 -t freebsd-ufs -b 552 -s ..... ada1 >gpart bootcode -b /boot/pmbr ada1 >gpart bootcode -p /boot/gptboot -i 1 ada1 > ># for data >gpart create -s GPT ada1 >gpart show >gpart add -i 1 -t freebsd-ufs -b 40 -s ..... ada1 Thanks Rozhuk, As it happens, I know how to create a GPT table and make sure the partitions are aligned. That's certainly a necessary step for getting good performance on AF-512e drives, but it doesn't have much to do with booting from an AF-4Kn drive. (Actually, since GPT is defined in terms of physical sectors, we can actually *stop* playing silly alignment games with AF-4Kn, since it is inherently aligned.) --rp >> -----Original Message----- >> From: owner-freebsd-hackers@freebsd.org [mailto:owner-freebsd- >> hackers@freebsd.org] On Behalf Of Jia-Shiun Li >> Sent: Monday, September 23, 2013 10:23 AM >> To: Ravi Pokala >> Cc: freebsd-hackers@freebsd.org; freebsd-hardware@freebsd.org >> Subject: Re: What's the state of AF-4Kn support? >> >> On Wed, Sep 18, 2013 at 10:49 PM, Ravi Pokala <rp_freebsd@mac.com> >> wrote: >> > >> > What you describe is the 'AF-512e' format - 4KB physical sectors >> > *emulating* 512B logical sectors. See [ >> > https://en.wikipedia.org/wiki/Advanced_Format#Advanced_Format_512e ; >> > http://www.idema.org/?page_id=2153 ]. With AF-512e, yes, the HDD >> > firmware does the read/modify/write for I/Os smaller than the >> physical sector size. >> > It is intended to be a low-cost/transitional format, allowing the HDD >> > vendors to get the advantages of 4KB physical sectors (better error >> > detection/correction algorithms, better areal density => lower cost) >> > w/o breaking compatibility with decades of firmware and software that >> > expect 512B logical sectors. >> > >> > What I'm asking about is AF-4kn - 4KB *logical* as well as physical >> > sectors. All the enterprise HDD vendors have told us is that AF-4Kn >> > drives expect data IO to be 4KB, and will reject smaller transfers. >> > (*metadata* IO - SMART, IDENTIFY_DEVICE, READ_LOG/WRITE_LOG, etc - >> > will remain 512B.) >> > >> > Doing some more digging, I found this post from ivoras which I missed >> > the first time around [ >> > http://ivoras.net/blog/tree/2011-01-01.freebsd-on-4k-sector- >> drives.htm >> > l ]; that tends to support my initial assessment - filesystem stuff >> > should Just Work[tm] - plus adds the detail that direct drive I/O >> (the >> > example he gives is trying to `dd' 10 bytes) will be rejected because >> > it is smaller than the raw-device access granularity. I've also >> looked >> > at 'ata_da.c' and see that adaregister() looks at both quirks and >> > IDENTIFY_DEVICE data to determine the logical block size. >> > >> > So, that leaves the bootstrap code as the remaining question-mark. >> > Does anyone what AF-4Kn support looks like there? >> > >> >> CC -hackers. >> >> Thanks for the clarification. Is there any 4Kn HDDs shopping now? I am >> not aware of any. >> >> BTW I believe UFS and ZFS have proper design for 4K-sectors, but >> FreeBSD needs some ecosystem connections to get samples early to test, >> incorporate supports and validate for it. Or we will need to wait until >> it appears on market and someone got caught into some kind of bugs. >> >> Regards, >> Jia-Shiun. >> _______________________________________________ >> freebsd-hackers@freebsd.org mailing list >> http://lists.freebsd.org/mailman/listinfo/freebsd-hackers >> To unsubscribe, send any mail to "freebsd-hackers- >> unsubscribe@freebsd.org" >
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