Best RAID Config for Server

Discussion in 'Mac Pro' started by gavinstubbs09, Sep 10, 2013.

  1. gavinstubbs09 macrumors 65816

    gavinstubbs09

    Joined:
    Feb 17, 2013
    Location:
    NorCal boonies ~~~by Reno sorta
    #1
    Hi everyone!

    We recently had a Mac mini server hosting 27 iMacs which just got really slow and we can no longer stand it. We are going to buy one of the Mac Pro severs (no trashcans here) and we need to have a certain setup. The Mini had a 256GB SSD for the OS and a 6TB external (which was in RAID1 so there was really 3TB space).

    So what would be the best way to have a 1TB drive for the OS and a 2TB drive for student data? Would it be best to order 2x 1TB drives and 2x 2TB drives and RAID1 them? My concern is disc access and write speed.

    Thanks!
     
  2. ScottishCaptain macrumors 6502a

    Joined:
    Oct 4, 2008
    #2
    I would recommend that you buy the Apple RAID card with your machine, and get Apple branded disk drives (the same drives you can select when you order your Mac Pro). If you buy the Applecare extended warranty, then your disk drives will be protected under that and getting replacements through Apple is a hell of a lot easier then trying to deal with Seagate/WD/Samsung/whoever directly.

    Contrary to popular belief on this forum, the Apple RAID card is a very solid unit. I've never had any problems with mine and it has been extremely reliable. I would probably buy 4x2TB drives with the Mac Pro and run them in a RAID 5 configuration, partitioned into 1TB for the OS and the rest for student data.

    -SC
     
  3. wonderspark macrumors 68030

    wonderspark

    Joined:
    Feb 4, 2010
    Location:
    Oregon
    #3
    My input is:

    The Apple Mac Pro RAID card is only useful if you use RAID 5. I'm a fan of parity RAID, and use RAID 6 myself in an 8-disk array, but that's external from my Mac Pro. The bummer of Apple's RAID is the battery conditioning that occurs at often-inconvenient times. If you can deal with that and require internal parity RAID, then it may be a good option.

    Western Digital is amazing to work with. They will even do advance RMA service, so you can keep using a failing drive while a replacement ships, thus allowing down time to be limited to about two minutes, or as fast as you can swap a drive. I use eight of the WD2003FYYS model in my RAID, which come with a 5-year warranty, and WD is excellent with customer service on replacements.

    My 2009 Mac Pro has had three Apple OEM 1TB HDDs internally in RAID 0 for nearly four years straight now, with no issues whatsoever. It's one of my scratch spaces, so no concerns if I lose it, and it gets 330MB/sec sustained. Just FYI.

    I'd skip the expensive Apple RAID card and just do either software RAID 1 or RAID 0 with a 4TB external HDD or two for backups, and put an SSD in the optical bay area for the OS. You can get 1TB SSDs for $600 now, which is cheaper than the Apple RAID card. These 4TB externals are only $180. I have a USB3 card in my Mac Pro which I use with a few of these, and they are fast and wonderful.

    You could do any number of combinations that make the most sense for speed, cost and reliability. I think the best balance is an SSD in the optical bay, three HDDs in RAID 0 and one backup 4TB in the four internal bays. That give you speedy boots and program launches, speedy data throughput, and backup space, all internally. You can even use a caddy or two here or there internally, and have more than just five disks internally.
     
  4. sgunes macrumors member

    Joined:
    May 25, 2009
    #4
    "My input is:

    Western Digital is amazing to work with. They will even do advance RMA service, so you can keep using a failing drive while a replacement ships, thus allowing down time to be limited to about two minutes, or as fast as you can swap a drive. I use eight of the WD2003FYYS model in my RAID, which come with a 5-year warranty, and WD is excellent with customer service on replacements."

    My experience with WD and Seagate is much worse. If one of your drives goes down, they replace it with some other schmuck's busted drive and reformat your unreliable drive and send it to someone else as "refurbished". I have a couple of them sitting around as I would not trust any data to a used and unreliable drive. At this point, I don't even bother to waste money on the returns and just trash drives that get flaky and start showing SMART errors.
    Fewer headaches and cheaper in the long run.
     
  5. ActionableMango macrumors 604

    ActionableMango

    Joined:
    Sep 21, 2010
    #5
    Everyone has different experiences.

    I had a Seagate literally blow up in the first week. Pop noise, smoke, scorch marks, the whole bit.

    I got on their website and entered the serial number. They knew it was covered automatically; no problems with dated proof of purchase. They cross-shipped, so the replacement was sent before they got my returned unit. IIRC, they even providing a printable prepaid shipping label, so they paid for shipping both ways.

    Replacement drive appeared to be new. Whether it's new or a refurb, it works perfectly.
     
  6. deconstruct60 macrumors 604

    Joined:
    Mar 10, 2009
    #6
    Your primary concern should be to do some measurements to see where the choke point is. 27 concurrent iMacs pulling reasonably large files off of a server can easily choke a under provisioned network. You need some metrics of how many concurrent clients are actively engaging the server. Higher average concurrency levels are generally oing to require more HDD spindles to keep up.

    Sure it would also swamp a single hard drive with that many clients, but you could currently have multiple problems. Increasing the HDD data transfer speed would only expose the other latent problem.

    This makes extremely little sense. Want to go from 3TB of space down to 2TB of space????? Why?

    Likewise changing the OS storage device to something slower is motivated by what? That isn't a problem in the current system so why change?
     
  7. VirtualRain macrumors 603

    VirtualRain

    Joined:
    Aug 1, 2008
    Location:
    Vancouver, BC
    #7
    Not sure why you need such a large volume for OS and why RAID1? Why not another SSD for your OS?

    For the data volume... RAID10 all the way for speed and redundancy (and no RAID card is required). You'll need 4 disks (the bigger they are, the faster it will be). 4x2TB will give you 4TB usable space, but if you can fill 3TB already, I'd go with 4x3TB for 6TB of space if your budget allows.

    I'm not sure what you backup strategy is, but you may have to budget for that as well (a single 4TB drive could do the trick for now).
     
  8. throAU, Sep 12, 2013
    Last edited: Sep 12, 2013

    throAU macrumors 601

    throAU

    Joined:
    Feb 13, 2012
    Location:
    Perth, Western Australia
    #8
    The best raid configuration is a case of "it depends".

    It depends what your priorities are: capacity, speed, resiliency, cost.

    Pick 2 priorities.


    • BIG/FAST: a bunch of drives in RAID0
    • BIG/RELIABLE: RAID6
    • BIG/CHEAP: RAID5 or JBOD
    • RELIABLE/CHEAP: RAID1 mirror
    • RELIABLE/FAST: RAID10, RAID60, other custom array RAID level (zfs mirror, RAID-DP, etc.)

    "Speed" also depends on whether you are heavier on reads or writes. Mirroring is a lot quicker to write to than parity based RAID, as parity raid needs to read from all the disks in the stripe first to recalculate parity if any part of the stripe is written to. No parity = just write the changed block - the amount of drive IO for a single write is FAR less. e.g., a RAID1 mirror vs 4 drive RAID 5 for a single write = 2 drive writes vs 4 reads (sure, from all drives at the same time, but they're busy doing that) and 2 writes (assuming the blocks on 1 drive are changed).

    If you are heavier on writes than reads, steer towards RAID1 or RAID10. If you're much heavier on reads and not so heavy on writes, parity raid is fine, however...

    Avoid RAID5 if you can if reliability is important (especially on big SATA drives > 1TB), drives are big enough these days that a second drive failure before the rebuild to spare completes is reasonably likely. Parity RAID also suffers BADLY in terms of throughput whilst rebuilding.

    Buying drives of a larger size than you need (and making smaller partitions on them, leaving 50% of the space unused and unallocated - i.e., short-stroking) can help with speed as it limits the movement of the drive heads which is a major problem for spinning disks when working hard with multiple users. Also, it keeps them on the faster initial tracks on the disk - the way hard drives work, the outer tracks are "faster" than the inner tracks.


    edit:
    Of course, all of those RAID options may not be available in a Mac Pro (RAID60 needs 10+ drives for example). Also, consider putting a heap of RAM in the machine to be used for cache to try and take some of the load off the disks during IO peaks.
     
  9. beaker7 macrumors 6502a

    Joined:
    Mar 16, 2009
    #9
    Havent had an Apple Xserve RAID card fail, out of 3.

    Had 4 of the Mac Pro Apple RAID cards, all 4 failed.
     
  10. freejazz-man macrumors regular

    Joined:
    May 12, 2010
    #10
    jeez, just get a NAS. If you have a directory service they can integrate with the permission schemes anyway - so I have a very difficult time understanding the purpose of a mac pro as a file server for the amount of space you are looking to share.
     
  11. ChrisA, Sep 13, 2013
    Last edited: Sep 13, 2013

    ChrisA macrumors G4

    Joined:
    Jan 5, 2006
    Location:
    Redondo Beach, California
    #11
    Finally some one who understands the issue. Read the above quote again.

    First figure out where is the problem. It very well could be your network or it could be the disk drives. I doubt a bigger CPU will help much at all. You might spend a ton of mont on the Mac Pro only to find it is no faster than the Mini because the Mini's CPU was never running at 100%.

    You might want a server with multipl 1Gig Ethernet cards, with 27 users you likely do want multiple cards and not only that but GOOD cards

    Next look at the disk IO subsystem. What is it's expected performance. Now divide that by 27 and is is still good? (27 is the worst case where every user pulls a big file at the same time, OK that unlikely. So divide by 10 or 5. Is the number still good. Likey the RAID-5 system is not fast enough if you assume a worst case. Some kind of mirrored system can be twice as fast.


    NOW, the hard part. How do you plan to back this server up? The rule should be to have three copies of the data at two different locations. Each RAID box counts as one copy. Backup servers don't have to be fast they run 24x7 in the backgroud doing something like rsync. In any case you need a plan. pay for a cloud service?

    I'm just saying that blindly buying a bigger computer may not be the best plan.


    EDIT: I just re-read the OP's requirements. It's a really small amount of data. If your data is only a few TB, use SSD for the data and buy TWO 4GB drives for Time Machine. This will give you redundant backup. Then buy two more hard drives and keep them off-site and rotate one at a time back to be refreshed. periodically.
     
  12. phrehdd macrumors 68040

    phrehdd

    Joined:
    Oct 25, 2008
    #12
    In general I would agree to get a good NAS set for both speed and redundancy.

    The original post didn't mention how the Mini server was set up. Was it only a storage solution or was it doing other server work. If the latter, then it makes more sense to get a separate "box" for storage and let the original server behave as a server or applications server.

    Some of the challenges come from what permissions each user has as giving total permissions to storage can impact performance depending on the vehicle for communication (TCPIP, NFT, AFP etc.).

    Check out Synology, QNAP, and a few other NAS options and see if they meet your needs. As for drives, everyone has a bum luck story to tell about a given brand or model. I have had great results from all the makers and also certain models were poor performers. I have to laugh that the best drives I have had (other than some SCSI drives years ago) turned out to be 5 Samsung 2 TB drives that just keep going and going and going. I go them when they first came out and they are still going strong.

    Try to plan your drive volumes so that they are never filled more than about 70 percent. Degraded performance (mechanical drives) start to mysteriously show up when volumes get too full.

    Given you require such a small amount of space to share, consider a fast 4 drive NAS set at 10 or maybe get ballsy and find one of the older QNAP or Synology NAS that take 2.5 drives and get some Samsung 840 Pro or EVO drives or OWC's higher end SSDs. Just make sure you get the ones that work well in a NAS.

    In your shoes, I would have a Main or Primary server to handle permissions and privileges, another for applications and separate location for mass storage needs. Also get quality routers/switches and if you go wireless, make sure you get higher grade components and not home wireless type units. Lots of people don't realize that routers/switches can create bottlenecks when not set up correctly/tweaked to work with certain loads.
     

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