Date: Sat, 16 Feb 2013 16:44:06 +0100 From: "C. P. Ghost" <cpghost@cordula.ws> To: Jens Schweikhardt <schweikh@schweikhardt.net> Cc: questions@freebsd.org Subject: Re: Should I bother with a gvinum stripe when using a pair of SSDs? Message-ID: <CADGWnjVJqm_s%2BWzF9_=Wt6tCg8kODbZor5-JXe-wdbiTBaZf=Q@mail.gmail.com> In-Reply-To: <20130216144751.GC3070@schweikhardt.net> References: <20130216144751.GC3070@schweikhardt.net>
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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. Since you're going SSD, I suspect that maximizing total storage capacity is definitely not your primary concern, right? In this case, you probably won't need some space-saving RAID variants (like RAID-5, RAID-Z, ...), therefore simple striping or mirroring would be adequate. However, striping puts your data at risk: lose one SSD, and the whole volume becomes unusable. Mirroring would at least preserve some redundancy. Moreover, by NOT using ZFS, you're sacrificing the by-sector checksumming that becomes rather important with SSD whose mode of failure tends to favor single (silent!) sector corruption that may go undetected for a while and grow worse over time. You may then want a mirrored ZFS configuration if this is a concern. Each solution has its pros and cons, and there are quite some trade offs in there. > Regards, > > Jens > -- > Jens Schweikhardt http://www.schweikhardt.net/ > SIGSIG -- signature too long (core dumped) -cpghost. -- Cordula's Web. http://www.cordula.ws/
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