Date: Wed, 25 Jun 2008 08:23:01 -0700 From: soralx@cydem.org To: freebsd-hardware@freebsd.org Cc: alwin.roosen@webline.be Subject: Re: Would a Transcend USB Flash Module of 2GB work? Message-ID: <20080625082301.36dcc2d0@soralx> In-Reply-To: <50A3BEAB67F03F44A2A063D55FC14D37119163@sbs2003.Webline.local> References: <50A3BEAB67F03F44A2A063D55FC14D37119163@sbs2003.Webline.local>
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> [...] > I am also wondering if it is a good approach to use USB dongles, > instead of real Solid State devices on ATA. I see a lot of USB problems > in the Mailing list Archives (see link below as example). I don't > understand all of that, and I know there are many USB devices which can > cause these issues. My hardware supplier recommends the USB dongles, > because they are cheaper and easier to install (just plug it in an 10-pin > USB port on the motherboard). > [...] I'm a bit short on time at the moment, I shall be brief. I could expand on this later, be sure to remind me. USB flash drives don't work for anything other that temporary portable storage. They are _completely_ useless for keeping base system on, even if you have lots of RAM and don't need speed. I tried 4 USB drives (30MB/s read, 20MB/s writes datasheet) connected to two EHCI mainboard headers, striped in ZFS. Totally useless. The avg real life write speeds are ~5MB/s, reads ~12-20 MB/s, (four 'dd' reads give total 80MB/s), and the whole array is only good for about one(!) IOPS. The whole system freezes for seconds or tens of seconds at times. I'm not sure if it's hadrware limitation, or just kernel's USB stack implementation (which, IMHO, is quite flaky and ugly anyway) that's at fault. UFS without softupdates give write performance (while copying /boot/kernel) of a few kilobytes/s (well, maybe few hundred, if it feels like it). Short answer: don't waste your money. Small 46 mm hard drives are better (but not completely noiseless). [SorAlx] ridin' VN1500-B2
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