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A quick little question about Raid
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A quick little question about Raid

TazTaz Member
edited June 2012 in General

So I have a guy here Who claims
"Software Based RAID 1 is better than Software Based RAID 10

Hardware Based RAID 10 is Better than Hardware based RAID 1

"

Is that true when it comes to Read/Write Speed?

Comments

  • AlexBarakovAlexBarakov Patron Provider, Veteran

    Software RAID 10, tends to fail from time to time, atleast this is what I am aware of. However, HW RAID is better than software RAID, at anytime.

  • BlueVMBlueVM Member
    edited June 2012

    Software Raid1 will be faster than Software Raid10... (Raid1 will have lower overhead)
    Hardware Raid10 is going to be faster than Raid1... (Raid10 will have a higher I/O)

    The reason is that software raid will use system resources and when the server starts to slow down raid10 will require more processing power and thus will be slower than raid1. Hardware raid10 would simply be faster because you literally have double the I/O capacity.

  • mikhomikho Member, Host Rep

    @LiquidHost said: HW RAID is better than software RAID, at anytime.

    +1 on this

  • @LiquidHost said: HW RAID is better than software RAID, at anytime.

    Not when you want to move hard-drives from one computer to another.

  • NickMNickM Member

    @Daniel said: Not when you want to move hard-drives from one computer to another.

    If you're doing that, you should be moving the entire array, right? So, just move the RAID card along with the drives.

  • rds100rds100 Member

    RAID1 (software or hardware) usually allows you to easily recover the data in case of some big failure that should never happen.
    I.e. you just take out the HDD, move it to another machine (without any RAID) and you can recover the data. This is not possible with the other RAID levels.
    And RAID10 (software or hardware) should perform roughly Nx times faster than RAID1, depending on the number of disks (i.e. RAID10 with 4x disks is roughly 2x faster than RAID1 with 2 disks).

  • AnthonySmithAnthonySmith Member, Patron Provider
    edited June 2012

    Probably worth pointing out with all the bizarre statements I have read so far (apart from rds100) SW raid/Fake raid are often referred to as SW raid when they are actually pretty different.

    For example you can SW raid in windows, you can add a cheapo sata card that claims to do raid 10 but is actually just fake/soft raid even though there is HW involved, and then on board raid which is pretty much the same as the previous.

    And then you have mdadm/ Linux Raid, which is actually pretty damn efficient even when compared to HW raid for cards under the $4 - $500 mark, however this does use your CPU cycles, not much but it does, mdadm is often bundled in with the other SW raid's however it is head and shoulders above them.

    Either way, raid 10 will always perform better than raid 1 in any fair test, simple as that.

    The issue I have with allot of this is people are so used to reading SW raid = bad and HW raid = good that they just regurgitate it over and over with no consideration for what the actual underlying tech is.

    Someone may post, "My new server will have HW raid" assuming that it must be HW raid because the hard drives attach to the o/b raid controller".... then every body gives them a pat on the back and celebrates without asking any further questions.

    The same person could post the same thing but say "SW raid" and everyone would jump on the band wagon and want to publicly stone them, when they actually meant mdadm, which would wipe the floor with the o/b raid mentioned previously...

    so yeah, how long is a piece of string exactly if you cant find the centre?

  • I've never seen Software RAID 1 perform faster then Software RAID 10, there is next to no overhead for striping. (Or mirroring for that matter, if you have a modern processor and a modicum of "spare" memory).

  • mikhomikho Member, Host Rep

    @Daniel said: Not when you want to move hard-drives from one computer to another.

    why would you?

  • miTgiBmiTgiB Member

    @MikHo said: why would you?

    Hardware failure, hardware upgrade off the top of my head

  • TazTaz Member

    Guys the debate is not about hardware vs software raid but 1 vs 0+1 on software (maddam) raid when it comes to performance.

  • pcanpcan Member

    According to my experience, the major shortcomings of software RAID are:
    1) When a disk start to develop bad sectors (partial disk failure), the hardware RAID controller marks the disk as dead after some retry, then disk operation resumes in degraded mode until disk is replaced. You can use the server without interruptions. When the same happens in software RAID, the operating system always retries to access the drive, and the server could become stuck at the next boot.
    2) Raid cards have a battery backed-up Ram or other non volatile storage for the cache content. If you enable write back caching on a software RAID, a server crash or blackout could damage the data.

  • CoreyCorey Member

    In software raid we experienced data corruption that required fsck and sometimes that didn't help. The corruption happened when these conditions were met..

    -Power Failure
    -Capped CPU
    -Disk Failure

  • We've never had any issues with SW raid (with Write caching disabled). We've had to failures with HW raid.

    But then I am sure, on a different day with a different server SW raid would fail and HW raid would prevail.

    I'd only ever use HW raid religiously where parity calculations are required

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