Date: Thu, 8 Mar 2018 17:02:38 +0100 From: Bernd Walter <ticso@cicely7.cicely.de> To: bob prohaska <fbsd@www.zefox.net> Cc: ticso@cicely.de, freebsd-fs@freebsd.org, freebsd-arm@freebsd.org, freebsd-current@freebsd.org Subject: Re: best settings for usb2 and attached disks, and sdcards Message-ID: <20180308160238.GD80981@cicely7.cicely.de> In-Reply-To: <20180308152611.GA61027@www.zefox.net> References: <1520403325.3513270.1294320744.0B1DE142@webmail.messagingengine.com> <20180308094636.GA80981@cicely7.cicely.de> <20180308152611.GA61027@www.zefox.net>
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On Thu, Mar 08, 2018 at 07:26:11AM -0800, bob prohaska wrote: > On Thu, Mar 08, 2018 at 10:46:36AM +0100, Bernd Walter wrote: > > > > I'm currently very pleased with the SanDisk Extreme Plus micro SD > > cards. > > They are quite expensive, but behave way better with random writes. > > > I don't think I've seen Sandisk Extreme Plus devices, how do they differ > from "ordinary" Sandisk extreme devices? I think there is a "Pro" version, > is that the same thing? I don't know any other SanDisk Extreme SD cards than the Extreme Plus I have. The Ultra, I usually use, have those typical long delay problems, while the Extreme Plus never showed up in gstat with more than 100ms absolute worst case, usually below 25ms under random write load with 4-8MB/s datarate. Those I have are labeled as SDSQXBG-032G-GN6MA. > > Event better in random write performance are the SanDisk Extreme > > USB sticks. > > Also quite expensive though and quite big. > > > Likewise, my experiece, spread over 4 RPi2's and 2 RPi3's, has been good. > > > I can't tell, however, if they are better in case of power loss > > related data corruption. > > > > Never done a systematic test, but accidental unplugs and power cycles > after a crash have never caused problems fsck -f won't fix. I've had those problems with any kind of card I've used. This even happened for me with fully readonly mounted cards. Cards have to do ocassional refresh writes for reads, which means at low level there's no such thing as read-only, but it is amazing that customers even mange to catch those. The Extreme Plus however are new for me and I can't tell yet. At least they are way better during development. So far I've went to NFS, but NFS has a higher latency and 100MBit ethernet is slower than local cards could deliver. -- B.Walter <bernd@bwct.de> http://www.bwct.de Modbus/TCP Ethernet I/O Baugruppen, ARM basierte FreeBSD Rechner uvm.
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