Software RAID 0 stinks up the place

Posted:
in Current Mac Hardware edited January 2014
Anandtech just tested two Raptors(10k IDE) drives in a RAID 0 configuration ran by the motherboard RAID softare. I often hear RAID overyhyped especially amongst the Mac crowd that pines for more drive bays. However I was unprepared for the amount of suckology that this test produced. Now this isn't because of RAID as a technology but I think it's important to realize that there is more to RAID than taking two drives and linking them. RAID works best with a dedicated controller that handles the data with little CPU intervention. Software RAID involves using your CPU for far too much to glean a huge difference in many cases.



Final Words



Quote:

If you haven't gotten the hint by now, we'll spell it out for you: there is no place, and no need for a RAID-0 array on a desktop computer. The real world performance increases are negligible at best and the reduction in reliability, thanks to a halving of the mean time between failure, makes RAID-0 far from worth it on the desktop....Bottom line: RAID-0 arrays will win you just about any benchmark, but they'll deliver virtually nothing more than that for real world desktop performance. That's just the cold hard truth.



Ouch! Guess there truly is no free lunch. However let's be honest. If Software RAID was "that" easy Apple, DELL and anyone who cares about performance would have designed it into the system.



Thanks Anandtech..you just saved me the hassle of buying two HD.

Comments

  • Reply 1 of 11
    johnqjohnq Posts: 2,763member
    Um, doesn't everyone know RAID 0 isn't really RAID anyway?



    Wikipedia puts it best:

    "RAID Level 0 is not strictly RAID since there is no redundancy?failure of one disk leads to data loss, as also happens in a related form of storage known as JBOD (Just a bunch of disks)"
  • Reply 2 of 11
    hmurchisonhmurchison Posts: 12,116member
    I guess you can call RAID 0 "redundant dataloss"
  • Reply 3 of 11
    johnqjohnq Posts: 2,763member
    Quote:

    Originally posted by hmurchison

    I guess you can call RAID 0 "redundant dataloss"



    Just think of the "zero" in RAID 0 as meaning "Zero Redundancy" and you'll be all set... I mean, if you avoid using it.
  • Reply 4 of 11
    g-newsg-news Posts: 1,107member
    I can tell you that software RAID 0 with 2 decent drives on two separate channels/busses under OS X is very, very fast.

    At least much faster than a single drive.

    Don't judge RAID 0, if you've never seen it yourself.
  • Reply 5 of 11
    johnqjohnq Posts: 2,763member
    Quote:

    Originally posted by G-News

    I can tell you that software RAID 0 with 2 decent drives on two separate channels/busses under OS X is very, very fast.

    At least much faster than a single drive.

    Don't judge RAID 0, if you've never seen it yourself.






    Sure, it's definitely faster. Just no redundancy.



    So, if you are used to one non-RAID disk (like most people), you'd really love a RAID-0 setup speedwise. Just remember to backup somehow.



    Not knocking it...
  • Reply 6 of 11
    ipodandimacipodandimac Posts: 3,273member
    Mac Addict reviewed G5 Jam in their latest issue--they said the performance gains after RAID 0-ing the 4 SATA drives was incredible.
  • Reply 7 of 11
    g-newsg-news Posts: 1,107member
    Quote:

    So, if you are used to one non-RAID disk (like most people), you'd really love a RAID-0 setup speedwise. Just remember to backup somehow.



    Sure, using a RAID 0 for sensitive data or maybe eben the OS is probably not such a good idea.

    But having one as scratch disk, serving data off it etc will make you not want to go back to a single drive anymore, ever.

    Unless get a RAID 5...
  • Reply 8 of 11
    hmurchisonhmurchison Posts: 12,116member
    I don't wanna hear from Macaddict "This RAID was so fast!" I want to see benchmarks. Realworld action.



    I want to see CPU utilization. RAID doesn't make sense if you gain storage speed but lose %30 CPU.



    The reason why people spend thousands on xRAID is because once your CPU iniates the I/O of your storage the RAID chipset handles much of the work without CPU intervention. It's why SCSI has always been good at this but expensive.
  • Reply 9 of 11
    g-newsg-news Posts: 1,107member
    On my Dual 1.25GHz G4 having the RAID 0 run full blown (serving files over gigabit E.net for example) I get about 30% CPU load on both CPUs. I'd hardly call that substantional, given it's a SOFTWARE solution. (pumping 90MB/sec over the net). On normal use the CPU load is between 5 and 10%. 0% when the drives are not accessed.

    I guess it depends a lot on the software though, I've heard of software solutions on a Wintel machine that grabbed the CPU so much it wasn't funny anymore.
  • Reply 10 of 11
    merovingianmerovingian Posts: 436member
    Quote:

    Originally posted by hmurchison

    Ouch! Guess there truly is no free lunch. However let's be honest. If Software RAID was "that" easy Apple, DELL and anyone who cares about performance would have designed it into the system.



    Thanks Anandtech..you just saved me the hassle of buying two HD.




    RAID striping is only really useful for large files that need fast access times, and OS files and the like are not a part of that. Striping will only work efficiently if the stripe size is chosen correctly, and there are a few ways of working this out. Many OS files are quite small, often in the KB range, meaning of course one will not notice an increase in I/O performance.



    It is my belief that all desktop computers should utilise RAID in some way, namely drive mirroring, i.e. RAID 1. We can all have a computer that malfunctions, but we never want to actually lose information stored on the computer... m.
  • Reply 11 of 11
    o-maco-mac Posts: 777member
    Have you ever considered using DASD?
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