4/3 RAID 3 or RAID 5 for an NFS server supporting a small workgroup?
Files can be large (100's of MB but less than 1 GB) and users will
have the ability to write locally to the RAID (as well as through
NFS). Just to be clear, the machine will support typical user
activities as well as serve the large files. Lots of reading and
writing both small and large files. Benchmarking using iozone
is inconclusive. I am leaning towards RAID 3, though. This is a Solaris
Enterprise-class server. Anyone have any real-world experience
with which yields better performance? Thanks. --dim
\_ Idiot. There are probably hundreds of papers on this, online,
yet you ask onthe motd. Then ignore the BEST advice, which is
to scrap both of them and use 1+0.
RAID3 can be faster, but performs worse in degraded mode,or
something like that.
\_ What class server? It kind of depends, since if you have something
like a 4500 available, you're not going to notice any performance
impact for most things a "small workgroup" will be able to do.
Also, you'll want to know how much i/o your disks (array?
internal? SCSI? Fiber?) can handle at any given time, since if
you're doing a lot of moving stuff around, your bus may choke
before you need to start worrying about RAID performance. Also
maybe play with different stripe sizes. I'd tend to RAID5, just
because I've had too many disks puke on me, and because I
usually don't need to do a lot of writes, assuming you can't do
0+1. -John
\_ Oh yeah, if you run Veritas, version 3 can do 1+0, which is
pretty spiffy. -John
\_ They both suck. Use 0+1, disk is cheap. -tom
\_ tom is right. Unless your RAID 5 is hardware RAID 5
with a serious RAM buffer, your performance will lag.
Test it yourself by making a RAID 5 partition and 0+1
on the same machine, and do some benchmarks. Here's
some numbers to give you a feel:
time mkfile 1024M test
Raid 0+1 Ultra 450 2 X 296 MHz:
0.0u 21.0s 0:52 39% 0+0k 0+0io 0pf+0w
NO Raid, Single disk, Ultra 450 2 X 296 MHz:
0.0u 17.0s 1:28 19% 0+0k 0+0io 0pf+0w
Hardware Raid 5 Ultra 2 2 X 296 MHz:
0.0u 18.0s 1:37 18% 0+0k 0+0io 0pf+0w
Software Raid 5 Sparc 20:
3.0u 158.0s 19:13 13% 0+0k 0+0io 0pf+0w
(One of the twinks out here is using this as a home
directory server for the whole department and
can't figure out why everyone is complaining
that things are slow) -ax
\_ not that I dont agree that sw RAID 5 can be hazardous
to Sysadmin health, but is it appropriate to compare
software RAID 5 on a sparc20 running at what, 150MHz
max, versus dual ultra hardware RAID 5 , stripe/mirror
or simple filesystems? --Jon
\_ Thanks for the ideas, guys. I hadn't thought of
comparing to 1/0 numbers, so I configured that way
also. This is an E450 4x400 MHz running a SUN
StoreEdge RAID (hardware RAID). The disks are 18 GB
Fujitsu's (SUN OEM). RAID 3 beat even RAID 1/0 in
many benchmarks on this system. Even when not, the
differences weren't much. --dim
\_ raid levels have different performance characteristics
for different workloads --jon
\_ 0 - normal
1 - nothing gained from mirroring
2 - does this even exist?
3 - higher handwidth
4 - does this either?
\_ Yes, NetApps use RAID-4, but most other
systems skip straight to RAID-5.
5 - lower average latency
6 - obviously I have no idea what I'm talking about
but I was smoking pot and felt compelled to
\_ DON'T FORGET. MICROSOFT INVENTED RAID SO IT MUST BE GOOD.
\_ I thought Al Gore did.
\_ you know al gore NEVER said he invented the
internet.
\_ Oops, I meant created: "During my service in the
United States Congress, I took the initiative in
creating the Internet."
\_ THIS MAN WANTS TO BE OUR PRESIDENT. RUN FOR
YOUR LIVES!
\_ Actually yes. Al Bore isn't as
smart as Bill C. His wacko ideas
about the environment will derail
progress and prosperity in this
country and throughout the world.
His weak foreign policy will allow
RED CHINA to attack/seize Taiwan
resulting in the unnessary loss of
life of the Taiwanese people. We
also won't get involved until its
too late and will probably lose the
first few encounters resulting in
the loss of American Lives. GW isn't
great (I voted for McCain), but
he's not a kook like Bore.
\_ people still say things like
Red China? Didn't that go out
with the 60s? Let me guess,
you are Taiwanese?
\_ got coke? -gwbush
\_ NO, MICROSOFT INVENTED EVERYTHING, INCLUDING THE
INTERNET. MICROSOFT IS PROMOTING INOVATION.
\_ Indeed. TCP/IP is listed as a Microsoft
protocol in Win95/8.
\_ Where are they gonna put it? Banyan,
"Da Internet", Bill Joy? It's their stack.
\_ Al Bore invented M$. His daughter still
works there.
\_ real world experience shows that people who think
that their one answer is the answer to everything
get fired in less than 10 years.
\_ who wants to work for a company that forces you to choose
between unattractive options? -tom
\_ I refuse to believe tom is this annoying. Stop
your odious mocking. -tom #1 disillusioned fan
\_ you must learn to think OUTSIDE THE BOX!
\_ are you in IDS 130?
say something.
\_ Thanks, but it's not an option. Neither is a NetApp. I
appreciate the help, but I'd like to stay within the parameters
I laid out.--dim
\_ Well, both your options suck. Real-world experience
is that it's a waste of time trying to help people choose
between two bad options. -tom |
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