RAID0 vs. RAID5 - Benchmark

Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

about how many percent goes the benchmarkable speed down when I change a
RAID0 Sytem with 4 hard disks to a RAID5 System?

Ingo
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More about raid0 raid5 benchmark
  1. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    Ingo Seibold wrote:

    > about how many percent goes the benchmarkable speed down when I change a
    > RAID0 Sytem with 4 hard disks to a RAID5 System?
    >
    > Ingo

    Depends a lot on the controller. RAID5 will be slower to write unless you
    have an extremely evil controller, but with a good RAID5 controller, reads
    could match those of a RAID0 system, although the calculation would be:

    RAID0 speed with X disks == RAID5 speed with X+1 disks.

    At least that's what I'm told :)

    Either way, the security provided by RAID5 is invaluable, the SX4000 has
    been my best spent money in a long time!

    --
    I win!
  2. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    Previously Ingo Seibold <inseke-news@yahoo.de> wrote:
    > about how many percent goes the benchmarkable speed down when I change a
    > RAID0 Sytem with 4 hard disks to a RAID5 System?

    If you have reasonably fast disks the read speed will be limited by
    the PCI speed, unless you have 66MHz PCI, 64 bit PCI or PCI-E and a
    matching RAID controller. Write speed depends on the card. I have had
    an Adaptec SATA RAID5 card reading and writing slower than Linux
    software RAID.

    In short: Reading should be about the same, maybe a bit (25%) slower.
    Writing is impossible to tell without knoing the details of the
    RAID% and the RAID0 solution being compared. Usually knowing
    the details will still not be enough and actual benchmarking
    is the only option.

    And of course it depends on the specific benchmark used.

    Arno
    --
    For email address: lastname AT tik DOT ee DOT ethz DOT ch
    GnuPG: ID:1E25338F FP:0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F
    "The more corrupt the state, the more numerous the laws" - Tacitus
  3. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    Arno Wagner wrote:

    > Previously Ingo Seibold <inseke-news@yahoo.de> wrote:
    >> about how many percent goes the benchmarkable speed down when I change a
    >> RAID0 Sytem with 4 hard disks to a RAID5 System?
    >
    > If you have reasonably fast disks the read speed will be limited by
    > the PCI speed, unless you have 66MHz PCI, 64 bit PCI or PCI-E and a
    > matching RAID controller.

    Depends on the size of the array and the data pattern. If the data is such
    that most reads are sequential then the bus could be the limiting factor.
    If most reads are of random sectors then access time is still going to
    dominate.

    > Write speed depends on the card. I have had
    > an Adaptec SATA RAID5 card reading and writing slower than Linux
    > software RAID.
    >
    > In short: Reading should be about the same, maybe a bit (25%) slower.
    > Writing is impossible to tell without knoing the details of the
    > RAID% and the RAID0 solution being compared. Usually knowing
    > the details will still not be enough and actual benchmarking
    > is the only option.
    >
    > And of course it depends on the specific benchmark used.
    >
    > Arno

    --
    --John
    Reply to jclarke at ae tee tee global dot net
    (was jclarke at eye bee em dot net)
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