Date: Sat, 16 Feb 2013 19:34:49 +0100 From: Jens Schweikhardt <schweikh@schweikhardt.net> To: "C. P. Ghost" <cpghost@cordula.ws> Cc: questions@freebsd.org Subject: Re: Should I bother with a gvinum stripe when using a pair of SSDs? Message-ID: <20130216183449.GD3070@schweikhardt.net> In-Reply-To: <CADGWnjVJqm_s%2BWzF9_=Wt6tCg8kODbZor5-JXe-wdbiTBaZf=Q@mail.gmail.com> References: <20130216144751.GC3070@schweikhardt.net> <CADGWnjVJqm_s%2BWzF9_=Wt6tCg8kODbZor5-JXe-wdbiTBaZf=Q@mail.gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On Sat, Feb 16, 2013 at 04:44:06PM +0100, C. P. Ghost wrote: # On Sat, Feb 16, 2013 at 3:47 PM, Jens Schweikhardt # <schweikh@schweikhardt.net> wrote: # > hello, world\n # > # > currently the only gvinum partition on my home system is a stripe for /home # > across two Velociraptor HDDs. I'm thinking of replacing the HDDs with a # > pair of SSDs. I was thinking of reducing complexity and in the migration # > possibly no longer use gvinum at all--one less thing to configure and worry # > about. # > # > * Would gvinum striping bring any speed advantage with a pair of SSDs? # > * Or am I hitting other limits so that striping SSDs is a waste anyway? # > * Should I finally take the plunge and acquaint myself with ZFS? # > # > System has 4GB RAM in an ASUS P5Q3 Deluxe with SATA II. It appears to me # > that SATA II with 300MB/s is maxed out by a single SSD and striping it # > will not improve r/w throughput. Is my simplistic reasoning correct? # # Jens, # # as always it depends on what you're trying to achieve: # - max speed / lower latency? # - max storage? # - max redundancy? # - max run-time-to-data-loss? # # Your choice of SSD probably means you'd like to reduce latency # and maximize data throughput. Exactly, when I started vith vinum many years ago in the magnetic HD age, striping with vinum gave me almost factor 2 in r/w speed as measured with dd. (I do backups regularly to other media, so data loss protection is not my primary concern). I realize that maximum SSD speeds as advertised by vendors and tests (e.g. 520MB/s for contemporary top notch SSDs) may only be reached under certain conditions far away from my normal usage, which is re-building worlds and kernels and ports on a daily basis. So if for my realworld working set a single SSD can deliver 300MB/s, striping with vinum just might get me a factor 2 again to 600MB/s across two SSDs. Then it would be worthwile to keep gvinum. Does that make sense? My understanding of SSD and SATA capabilities may however be completely dreamed up... Regards, Jens -- Jens Schweikhardt http://www.schweikhardt.net/ SIGSIG -- signature too long (core dumped)
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20130216183449.GD3070>