[TriLUG] Article Link: Slashdot Post on Disk Throughput...
William W. Ward
Wed, 7 Aug 2002 10:38:29 -0400
Since Tanner's been discussing different file system choices for the new
servers, I figured the enclosed link/article would be of interest to some of
you out there thinking about different RAID, file system and expected
throughput numbers with your disks. The actual good stuff is in the
comments, so be sure to set the comment filter to 2 or better and read
through many of them.
Amongst the better moderated comments, I found a good explanation of why
RAID5 is not a good choice for throughput OR redundancy in today's age, a
short blurb about using hdparm to improve disk throughput under Linux, and
ways to eliminate single points of failure for SANs, arrays and whatnot.
Working for a major company that throws money at problems rather than works
through system tuning and appropriate planning, I'm extremely interested in
this sort of information. When I finally relocate to the home data center,
I want to be able to subtly make some changes to improve the infrastructure
and get some real performance increases without spending any more money on
bad solutions. Anytime I come across these types of articles, I think it'd
be a great idea for someone to collect them and assemble them into a "best
practices" book for the sub-management admins doing the grunt implementation
Article starts off:
Mr. Jackson asks: "What kind of disk transfer rates (MB/s) do people get in
the real world when moving around large (100s MB) files? Either every
machine in our building is mis-configured, or our notions about what we were
getting are way off. I've tested half a dozen machines, mostly Win2k, some
Linux, by just copying a large file and timing it with a watch. 8 MB/s seems
to be about average for inter-disk copies. RAID 1 (stripped) got as high as
12 MB/s after fiddling with cache settings. RAID 5 was as low as 2 MB/s. We
all thought the numbers should have been around 30 MB/s."