Date: Mon, 13 Oct 2014 14:25:19 -0700 From: Lyndon Nerenberg <lyndon@orthanc.ca> To: Don Lewis <truckman@FreeBSD.org> Cc: freebsd-stable@FreeBSD.org Subject: Re: getting to 4K disk blocks in ZFS Message-ID: <E44D9624-D8A2-4CA5-B399-3C1983904CA9@orthanc.ca> In-Reply-To: <201410132047.s9DKlGxD030176@gw.catspoiler.org> References: <201410132047.s9DKlGxD030176@gw.catspoiler.org>
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[-- Attachment #1 --] On Oct 13, 2014, at 1:47 PM, Don Lewis <truckman@FreeBSD.org> wrote: > Combine that with raidz and now the > overhead is about 40%. Ouch! But ~33 of that 40% is generic RAID overhead, and has nothing to do with the 4K block size issue. (I.e., you would have 33% hit even if you were running UFS on a three disk RAID5.) On any real-world system where you're running ZFS, it's unlikely the 4K block overhead is really going to be an issue. And the underlying disk hardware is moving to 4K physical sectors, anyway. Sooner or later you're just going to have to suck it up. --lyndon [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- iQIcBAEBAgAGBQJUPEM/AAoJEG8PnXiV/JnU/fwP/i5a9ns87syp7G8aGMPVu7tk UMQilNakksxbIsVxmLk/qKgnktAaEX6e871KPSSAgB34EZkV5UCpdARMtCD1Vdmu iJVCdwqODtz2pgWYI7T1PYP2swnl2gpQvWt1SToMEITP0Tyqeqh184Cmj9fMoUI+ WwuIZ3emlF4VXBPCJxYDyR7BsbBEM8MMYzlwBxSGTTZzJoqoPwOMYrmx4fW3ALXe SnV7buUTSIMUYfIHfIlMDiOrfFS7/n8xy0cKFSyHCGW/uzTDVdfMEWzHZPc/ALQD 7+rQZRXTIHya/0xkksLnBTPZQ5o9/+PGZ5k0UIgGQCPFGXLSiRSHgsz/FGlg467i w+38g1933+iMTFoawmU4QV+YvrwWnddqcZbcqI6zM9kcCOy47LUJ7+oKildg421u AXOmVMEtJ6v27pK0xcBUqPGeP/GGzXvMZF4GV251iL7W7LcAqC8jLBVaRvT/uRYn U5h4IM4FDBQYsb3dW6N6mkjTXK3eo2hc7iwZnZCrA6qIxL5DqmbBxmrXC/wtuR/8 UFA7pS4qP+NKoTWXq7vxZhpm4KqZSBVCSoSQpNRUjhM/r++VUSRNsQYb01DSKj1F FOFCea+Opwgj1Na0/IWInecIeH9IcUQYyjD2y3l1aedhlvsmaFwkm1tF2J2FIu70 1jT9aCRZSkfcV9is5/nD =TiSk -----END PGP SIGNATURE-----
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