SAN/Enterprise storage people: What's your favorite raid level?

Discussion in 'OT Technology' started by trouphaz, Jun 20, 2008.

  1. trouphaz

    trouphaz New Member

    Joined:
    Sep 22, 2003
    Messages:
    2,666
    Likes Received:
    0
    I love me some RAID5. When setup properly, I haven't run into any problems with performance or reliability over RAID1 or RAID1+0. Obviously that means having enough cache to front end the writes. I still meet people, especially EMC people, who are so in love with the performance gain of RAID1 that they ignore the fact that they aren't pushing enough IO to stress RAID5.

    Anyway, what do you usually push for when implementing a new array? If a DBA came up and demanded RAID1 because that is fastest, would you just agree or would you argue for RAID5?


    Have you looked at RAID6? If your array supports it, would you rather use RAID6 instead of RAID5 to increase your data redundancy?
     
  2. crontab

    crontab (uid = 0)

    Joined:
    Nov 14, 2000
    Messages:
    23,441
    Likes Received:
    12
    ibraidz

    i have no favorite, i just use whatever the vendor recommends. i don't waste energy especially debating with the dba's on what raid groups are fast or fast enough, it's not worth it. why? the second there is a problem, they will blame the non-bp raid group wasting even more time.

    hardware side, i prefer storage that spans all disks, like eva vraid or 3par's chunklet's method. i don't like managing the monolithic method anymore.

    i have raid dp on my netapps. never needed the dual-redundancy, but it's nice to have i guess.

    for veritas, i usually mirror, concatenate, or stripe. i've seen raid 5 volumes sometimes take themselves offline even when one disk fails, which isn't supposed to happen.
     
  3. Dnepr

    Dnepr Guest

    RAID5
     
  4. dorkultra

    dorkultra OT's resident crohns dude OT Supporter

    Joined:
    Oct 14, 2005
    Messages:
    22,736
    Likes Received:
    27
    Location:
    yinzer / nilbog, trollhio
    raid 10 > raid 5
     
  5. trouphaz

    trouphaz New Member

    Joined:
    Sep 22, 2003
    Messages:
    2,666
    Likes Received:
    0
    oh, yeah. i'd never RAID5 with any software. that's just asking for trouble. RAID 0, 1 or 1+0 is ok, but anything else and you are asking for trouble.

    raid10 is best for low end stuff. when you get to mid-range storage RAID5 starts to get better because the array controllers are much better at managing the parity calculations + the cache is generally large enough to offset a lot of the write performance issues. on enterprise arrays, i've generally found that a well laid out array configured with RAID5 is sufficient for the average workload of many databases though there are certainly cases for RAID1+0 with some data. but, when you are working on a 150Tb array, 75Tb is an awful lot of storage to piss away. It is much better when you are losing 20-40Tb.


    i will always argue with the DBAs about RAID levels and spindle counts. their knowledge is no longer applicable. all they need to worry about is IO amounts and i will worry about my solution meeting their requirements.
     
  6. crontab

    crontab (uid = 0)

    Joined:
    Nov 14, 2000
    Messages:
    23,441
    Likes Received:
    12
    .

    But all the dba's here keep referring to are archaic documents over 10 years old about the number of spindles, where the data should reside on the disk, blah blah blah.

    i tell them, that doesn't apply when you're writing to 40 gb of cache.

    uhh, wat?

    this employer pisses away money anyway, so there's not real point in fighting them.
     
  7. trouphaz

    trouphaz New Member

    Joined:
    Sep 22, 2003
    Messages:
    2,666
    Likes Received:
    0
    right. see i just say, "ok, you need fast disks all around, but really fast disks for your archive logs or temp space and you don't want them to affect each other? ok, i can do that while still ignoring your comments about spindle counts and RPMs."
     
  8. dissonance

    dissonance reset OT Supporter

    Joined:
    May 23, 2006
    Messages:
    5,652
    Likes Received:
    1
    Location:
    KS
    Generally RAID6, but it depends on the use of the array.

    I would say that the majority of decent sized enterprise arrays are RAID6 and some RAID5. This is for the bulk of the discs, not the management SW/OS.
     
  9. trouphaz

    trouphaz New Member

    Joined:
    Sep 22, 2003
    Messages:
    2,666
    Likes Received:
    0
    i actually haven't used RAID6 at all yet. i think it was only introduced more recently in HDS arrays, though i'm not sure how long it has been (or if it even is) available on the DMX. it sounds interesting, giving much better redundancy while not chewing up half of your disk.

    in one way, RAID6 actually seems better for data reliability than RAID1 since RAID6 can sustain any 2 failed drives while RAID1 can only handle 1 (RAID1 only has 2 drives). RAID1+0/RAID10 can handle more than 1 failed drive as long as you never lose both drives in a mirrored pair.
     
  10. dissonance

    dissonance reset OT Supporter

    Joined:
    May 23, 2006
    Messages:
    5,652
    Likes Received:
    1
    Location:
    KS
    To be honest though, I don't really deal with solutions. I work on array cost and pricing as well as competition comparisons. So I look at data about common configurations and quoted configurations (both of our products and competitors products), but none of that goes into how the array was actually setup software wise (just what they bought).

    As far as HDS, just pulling up a quick reference, RAID6 is present on all of their arrays I have data on in this file. This is what they support:
    SMS100: 6
    WMS100: 0+1, 1, 5, 6
    AMS200: 0, 0+1 ,1 ,5 ,6 (RAID-0 Fibre Channel only)
    AMS500: 0, 0+1, 1, 5, 6 (RAID-0 Fibre Channel only)
    AMS1000: 0, 0+1, 1, 5, 6
    UPS-VM: 0+1, 1, 5, 6
    UPS V: 1, 5, 6

    Thats just what the first thing I opened states. I'd actually have to look to see when availability began....
     
  11. trouphaz

    trouphaz New Member

    Joined:
    Sep 22, 2003
    Messages:
    2,666
    Likes Received:
    0
    ah, no biggie. yeah, i know a lot of HDS stuff is listed as supported on the array, whether or not the end user can actually use it yet. so, they were saying that it could do sparse snapshots, but while the functionality existed it hadn't been released to the general public yet.
     
  12. deusexaethera

    deusexaethera OT Supporter

    Joined:
    Jan 27, 2005
    Messages:
    19,712
    Likes Received:
    0
    My favorite raid is multiple level 60's in Ironforge.

    :fawk:
     
  13. Peyomp

    Peyomp New Member

    Joined:
    Jan 11, 2002
    Messages:
    14,017
    Likes Received:
    0
    I like RAID 0. Cause fuck it! Their data means nothing to me.
     
  14. trouphaz

    trouphaz New Member

    Joined:
    Sep 22, 2003
    Messages:
    2,666
    Likes Received:
    0

    i'm embarrassed that i understood that. :)
     
  15. Mikey D

    Mikey D New Member

    Joined:
    Oct 13, 2002
    Messages:
    6,666
    Likes Received:
    0
    Location:
    Royal Oak, MI
  16. deusexaethera

    deusexaethera OT Supporter

    Joined:
    Jan 27, 2005
    Messages:
    19,712
    Likes Received:
    0
    :big grin:
     

Share This Page