Date: Thu, 4 Nov 2010 07:35:42 -0700 From: Jeremy Chadwick <freebsd@jdc.parodius.com> To: freebsd-fs@FreeBSD.ORG Subject: Re: Using an SSD "disk" for / Message-ID: <20101104143542.GA628@icarus.home.lan> In-Reply-To: <201011041429.oA4ETMsV088125@lurza.secnetix.de> References: <20101103030515.GA61758@icarus.home.lan> <201011041429.oA4ETMsV088125@lurza.secnetix.de>
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On Thu, Nov 04, 2010 at 03:29:22PM +0100, Oliver Fromme wrote: > Jeremy Chadwick wrote: > > As for the performance: it's something you'll have to see for yourself. > > The performance is outright amazing when it comes to administrative > > tasks (OS installation, newfs, massive copies of data to/from the SSD, > > updating /usr/src and /usr/ports, etc.). Try a build/install world or > > kernel sometime on an SSD and watch your terminal. You'll be pretty > > impressed. > > What kind of tuning do you apply to those file systems? > > I'm asking because I can't really reproduce those results. > On a machine with plenty of RAM I've created memory disks > for obj and src, which should at least be as fast (probably > even faster) than an SSD. Buildworld was somewhat faster, > compared to standard (well-tuned) UFS+SU filesystems on a > fast SATA HDD, but not _that_ much faster. In fact the > difference was small enough that I stopped using memory > disks and returned to using UFS+SU+noatime (and a few other > tuning options) on a HDD. > > So, if you experience a _dramatic_ speed-up when using SSDs > for buildworld, I would really very much like to know why > this is the case, and what kind of tuning you performed. Literally: absolutely no tuning. I treat the SSD the exact same as I would a standard mechanical HDD: install FreeBSD on it, and that's that. I imagine the performance difference greatly depends on what SSD you're actually using. Again, the Intel drives have the highest IOPS out there (at least in the consumer-grade market), and I can't justify the cost of an SLC-based drive, so I stick to MLC. Possibly you and I have different interpretation of what "dramatic" means? :-) My opinion is that cutting 6-7 full minutes off a buildworld is pretty dramatic. -- | Jeremy Chadwick jdc@parodius.com | | Parodius Networking http://www.parodius.com/ | | UNIX Systems Administrator Mountain View, CA, USA | | Making life hard for others since 1977. PGP: 4BD6C0CB |
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