Should I bother with a gvinum stripe when using a pair of SSDs?
schweikh at schweikhardt.net
Sat Feb 16 18:38:33 UTC 2013
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 at 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?
# 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...
Jens Schweikhardt http://www.schweikhardt.net/
SIGSIG -- signature too long (core dumped)
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