RAID 0 for new MacPro - planned setup - need advice

Discussion in 'Mac Pro' started by schweinsteiger, Apr 25, 2009.

  1. schweinsteiger macrumors member

    Mar 10, 2009
    I will receive my new 2.93Quad sometime next week and am trying to figure out the best performance and backup plan for me. I do graphic design, Quark, PS, Flash, have dozens of web tabs open, use EyeTV, have a large iTunes library.
    (I'm currently still on a 1.8DP G5 from 2004 .... and suffering from slow iTunes library issues etc)

    I want to install a striped RAID set with three 1TB Hitachi HDs.

    I want to partition each of the three HDs first:

    1. 30GB scratch (for PS) (total 90GB)
    2. 55GB system & apps (total 165GB)
    3. 250GB work files/data (total 750GB)
    4. 300GB new iTunes media (total 900GB)
    5. 300GB existing iTunes media (total 900GB)

    I would add one 2TB WD Green HD in bay4 and use CCC to backup partitions #2-4 daily

    I would use an external 1TB HD to backup the static 900GB of iTunes media from partition #5.

    I imagine this would give me fast performance for apps and secure backup in case one of the HDs in the striped RAID fails.

    BTW, if one of the RAID drives fails, how time-consuming is it to replace the content from my 2TB CCC clone? Do all three RAID HDs have to be re-written?

    What do you think of the proposed setup?
  2. schweinsteiger thread starter macrumors member

    Mar 10, 2009
    one more question....

    One question for the above mentioned setup is in regards to the partitioning ... Any disadvantages to 5 partitions? Would it be better (more flexible) to just have just 2 partitions (one for scratch disk, one for the rest) and then simply use different folders?
  3. NightSailor macrumors 6502


    Feb 24, 2008
    I don't like it, actually. This is RAID 0. It leaves you with nothing when it crashes. I think you need to separate the OS, or the OS and Apps, from the data. That is what I'd do. That way, if you lost the data, it is easy to restore, or if you lost the OS, it is fairly easy to restore. To restore everything is a PITA.

    Here is what I do.

    I boot off an Intel 160GB SSD and keep my Applications on there too, mounted in my optical bay. You could do this with a normal drive.

    I run four RAID 0 1TB Seagate drives with a 32gb/drive scratch disk, 128GB total, and the rest as a giant 3.51TB user drive. I back up externally. I'm getting around 360GB/s transfer rates on the scratch disk, and close to that on the rest of the RAID 0. These are older Seagates and have been problem free for me. I plan to update the OS and applications to a two SSD RAID 0 in the future.
  4. schweinsteiger thread starter macrumors member

    Mar 10, 2009
    I like the idea of all internal HDs. All content of the three RAID HDs would be automatically backed up to the internal 2TB drive. Apart from 900GB of static content (partition #5) that would be manually backed up externally when necessary.

    So in case of a RAID 0 crash I would boot from the 2TB drive in bay 4 and restore the three HDs.

    I guess that could be time intensive. But how often should I expect that to happen? If it happens once a year it would set me back one night of copying files back onto the three HDs ...

    It has crossed my mind to add a fifth small HD to the optical bay for system and apps only, instead of having these in a separate partition on the RAID HDs. Would that make the RAID 0 array safer?

    What's the downside of having the system and apps on the RAID HDs?
  5. schweinsteiger thread starter macrumors member

    Mar 10, 2009
    here's a modified setup - any opinions?

    Here's a modified setup:

    I would use 5 internal HDs, setting up three as a RAID 0 array.

    I would use the 640GB HD that comes with the Mac in the optical bay to host the system & apps.

    I would install a striped RAID set with three 1TB Hitachi Deskstar E7K1000 HDs.

    I would partition each of the three HDs first:

    1. 40GB scratch (for PS) (total 120GB)
    2. 280GB work files/data (total 840GB)
    3. 300GB new iTunes media (total 900GB)
    4. 310GB existing iTunes media (total 930GB)

    I would add one 2TB WD Green HD in bay4 and use CCC to backup partitions #2 and #3 and the "home" folder from the system HD daily.

    I would use 3 external 1TB HD2 to backup partitions #2, #3 and #4 once a week.
    I would use an external 750GB HD to back up the system & apps HD once a week.

    Fast performance for apps and secure (double) backup?

    As per, I think that an SSD for the system and apps is overkill at this moment. From what I understand it would give me lightning fast booting and app launch, but not faster app performance. So it would shave off a total of maybe a couple of minutes a day waiting for several apps to load but it wouldn't make them run any faster. ... But it would be way more expensive and hot.
  6. frimple macrumors 6502

    Nov 18, 2008
    Denver, CO
    Sorry if you posted this somewhere, I kind of scanned the thread and didn't see it. Is this software RAID or are you getting the card?

    Also, I think if you want to make a bunch of partitions out of one big "array" then your best bet is RAID 5 across as many spindles as you can throw at it. For example if you were going 3rd party hardware RAID you could use the second optical bay to store an additional 4 drives and have a huge 8 disk array.

    Some things to consider also. If speed is everything and you're looking at doing one large "fast" array consider some of your biggest space offenders. Does your media (which accounts for 2/3's of your space) need to have a throughput of 150 MB/s?? I would, (in your case) think about 2 OCZ SSD's in RAID 1 (or 0 if you want to get a little crazy... and I like crazy) and a 2TB drive. I think that would suit you just fine.
  7. nanofrog macrumors G4

    May 6, 2008
    It varies, and is difficult to predict. Your drives could last 3+ years before a failure, or as little as a few minutes. :eek: :p

    NO. If the stripe fails, whatever data is on it is gone. Having the OS/apps on a separate drive can speed up the recovery process. (Still boots, so less to load).
    Down side:
    If the stripe fails, you have to reload everything. OS, apps, and data.

    Up Side:
    OS and apps can load a little quicker, assuming you're comparing like technologies. (Not SSD vs. mechanical).
    You may be better off going with RAID 10 (assuming you're using OS X's software RAID functionality). It offers speed, and redundancy (which a stripe can't offer). (Obviously I'm no fan of RAID 0).

    A hardware implementation would be even better. They can offer better throughput, and other features the OS X software RAID can't. Additional array types, such as 5 or 6, on-board cache, and an IOP that removes the need for the CPU to handle processing.

    The partitions might help make files appear separate, and possibly help reduce some user errors like accidental deletion, but that's about it.

    Not all partitions would give the same throughput, depending on actual location on the platters. (Inner tracks are slowest/Outer tracks fastest). With RAID 0, you'd still have an issue with data loss with all partitions, as they're located on the same physical drive set.
  8. Tesselator macrumors 601


    Jan 9, 2008
    Looks fine to me.

    One thing I've noticed tho is that in a system with 8 or more GB of RAM PS never seems to use it's disk cache in normal use. If you're at 16GB or over such apps may never actually need a disk cache at all - so why create a separate partition when it's only going to get used once a month for a few moments or less?

    As memory gets cheaper I think the concept of maintaining a fast cache partition becomes more obsolete.
  9. schweinsteiger thread starter macrumors member

    Mar 10, 2009
    Do I need a RAID 0 setup at all?

    I've never done so much research before buying/setting up a new Mac before. I used to just buy something that made sense at the time, maybe get some additional RAM or HDs after I ran out of space/speed ...

    So this is the first time I'm putting a lot of effort in preparing a dream machine for my needs.

    I guess it's pretty easy to get into overkill mode when you visit enough forums. When you're reading up on an specific issue (like RAID) every expert on that forum usually just gives an opinion on the best setup, not the general usefulness.

    I got most of my RAID ideas from the very informative site.

    I would like to know if it makes sense for me IN GENERAL to set up a RAID 0 array?

    As I said, I work in graphic design, I use Quark, Flash and Photoshop. I often have multi-layered PSD files open, but never really bigger files than 100MB. I have a large iTunes library and it is very annoying that every time you play a song or simply browse through the playlists, the spinning beachball appears. Someone in a different forum once suggested that faster HD read/write times would help. (The last iTunes update 8.1 actually helped with big libraries)

    I'm planning to experiment with producing really large artwork in Painter or Photoshop, then I could be dealing with GB-sized files in the future ...

    So, please let me hear your opinions if for someone in my position a RAID array makes sense at all!

    From what I have read by now, it seems that you do get a nice performance bump. But I'm most worried about what happens when a disk fails. We do have 2 to 3 power outages every summer here in my neighborhood in Los Angeles. Is all gone when that happens, or just the last file you worked on?
  10. nanofrog macrumors G4

    May 6, 2008
    Disk caching has been around for awhile now, and memory has gotten both larger (capacity), and less expensive per unit (GB these days).

    Additional memory would give a speed boost to some extent, as the drive(s) only need to read the app, and write the data. No intermediate read/writes for disk cache. All on the slowest method of data storage in the entire computer. :eek: :p
    This can certainly happen, but how the question is posed might also make a difference. Wiki has become a decent source for basic RAID information.

    It depends on whether you like dealing with a failed array.

    A stripe set offers a speed bump, and very inexpensively if software RAID is used. But the data is in greater peril than on a single disk. At the very least, you need a good backup method, which fortunately, you're aware of. :)

    So the real question is, how much time are you willing to put into system repair when something goes wrong?

    If you need the system operational at any given time, RAID 0 isn't the way to go. You'd want to select an array type that offers redundancy as well. No form of RAID is completely risk free, but redundancy really does help. At least the rebuilds are automatic (assuming more drives haven't failed than the array type can handle).

    Each file is split across all drives, and is the reason if a single drive goes, all data is gone. In the case of a power outage, it depends on the details.

    If it was during a read, the data would still be there, unless you end up with a head impacting the platter (crash). On a write, data will be lost. The amount of data lost depends on the number of files being written at the time of the power failure. If you happen to be in the middle of a PS operation (write), the file would be damaged, and need to be redone.

    But if it occurs with an OS file, you could end up with a system that won't boot. :(

    Hence the reasoning to either use a redundant array, or place the OS on a separate disk.

    In any event, you'd be very wise to invest in a UPS for power outages, no matter what array type you select, if at all. Line power isn't constant, and it protects the computer from more than just an outage, including both over voltages and under voltages (brown-outs).

    Surge suppressors can't protect against a power outage (obviously), but it can't help with a brown out either. They can kill electronics, such as your new computer. :eek:
  11. schweinsteiger thread starter macrumors member

    Mar 10, 2009
    I hope the speed bump is big enough to justify jumping through all these hoops. Especially in iTunes it would be great to have a snappy, responsive system.

    The way I 'm planning to set it up, with an internal 2TB back-up HD and the OS & apps on a separate HD in the optical bay I thought I had the perfect situation. If something goes wrong I could just restore from the 2TB backup. I just have to make sure that I clone work data more often than daily ...

    Oh yes, I checked already and will get an APC BACK-UPS RS 1500VA with extra battery pack. That should give me 30mins in case of a power outage to save files and properly shut down.

    So in the end I still would have to weigh the pros and cons of a RAID0 setup. It seems with the proper backup plan, I would lose only a very limited amount of data in case of a power outage (maybe none at all with the UPS working well). In case of disk failure I would lose all data on all three disks and would have to restore all data from the backup HD. I know the likelihood of a disk failure goes up x3 with three HDs in an array. Still, I never had a HD failure in 18 Mac years. (Actually once on a PowerBook) ... but I don't want to jinx it by bragging here ....

    So, it seems a RAID 0 with three 1TB HDs would provide me in effect with one much faster 3TB HD. Is the better speed worth the x3 risk of disk failure?

    Have people here have had experience with disk failure, power outages etc? How many people use a RAID 0 array and like/dislike it?

    After a power outage, how do you know which files are damaged and need to be restored? (I don't want to overwrite a good backup copy with a damaged file when I back up the first time after an outage ...)

    Considering my specific work/leisure use situation - is it worth the trouble?
  12. schweinsteiger thread starter macrumors member

    Mar 10, 2009
    ... and another possible setup ....

    How about this:

    Four 1TB HDs in a RAID5 array. (for scratch disk/current work/iTunes media)
    One 1TB HD in the optical bay for OS & apps and static archived files.


    Four 1TB HDs in a RAID10 array. (for scratch disk/current work/iTunes media)
    One 1TB HD in the optical bay for OS & apps and static archived files.


    Either way automatically backed up to external HDs with CCC.

    Would this work with software RAID or do I need a card?
    Is a card better, in regards to safety (built-in battery) and performance?
  13. nanofrog macrumors G4

    May 6, 2008
    This strategy could work. :)


    To me, NO, as I place a high importance on drive availability. That is, the system remains operational within design limits of array types that offer redundancy.

    RAID 5 for example, can remain operational in case of a single drive failure. Swap the disk, and let it automatically rebuild. Granted it runs in a degraded state until the rebuild is complete, but you don't loose the ability to use the system.

    If you're making money with the system, I'd recommend you take a better look at other array types. The data is safer.

    If you still opt to go with a stripe, restore the data from a previous backup (most recent before the power failure).
    RAID 5:
    You need a hardware controller in a Mac. It can get a little more complicated in the '09 MP's, as the SATA connectors are soldered to the logic board. (No longer using a 4i MiniSAS cable).

    It may still be possible using both optical bays. Otherwise, you'd need to go with an external enclosure method. The down side, is the enclosure(s) and cable(s) add to the cost.

    RAID 10:
    OS X can operate this array. It would be better than a stripe, and solves the "write hole" issue inherent with RAID 5 or 6.

    Some hardware controllers offer an NVRAM solution to the "write hole", so don't let it scare you. Just be aware of it. (Read here for write hole).
  14. johnsonvideo macrumors newbie

    Aug 25, 2009
    Early 2008 Mac Pro and RAID 5

    I found this thread because I'm at the point of doing a RAID 5 with four 1.5TB Seagate Barracuda drives, and per Nanofrog's advice, moving the 320GB drive to the optical drive bay using a cable he recommended.

    A Mac Pro RAID card has been successfully installed, and is recognized in the PCI slot in "about this mac".

    I will use the disk utility to format the RAID 5, but since I can't start this process until my fourth drive comes, I haven't opened the utility to see what steps will be available to me.

    Therefore, these questions remain:

    1. There is mention on this thread the need for a stripe. No idea what that means. Do I need to stripe the four 1.5TB drives that will be known as a single drive to establish RAID 5? For redundancy, is RAID 5 safe, or should I be considering another RAID like RAID 10?

    2. Where does the cable Nanofrog recommends connect from the 320GB OS drive in the optical bay to my early 2008 Mac Pro's mother board?

    3. Lastly, could I put this 320GB OS drive in an USB enclosure, and successfully run the OS disk externally.

    Thanks, everyone, for your guidance.

  15. UltraNEO* macrumors 601


    Jun 16, 2007
    Ummmm RAID0? Great concept, not very practical.

    Personally I wouldn't use RAID0 for anything that's personal or any form of media storage, the risks are just too high! Doesn't matter how many partitions you have it's still two physical drives with zero redundancy - essentially Two drives, one fail, lose everything!!

    RAID0 only good for a project drive where speed is essential and the content is temporary/disposable, even then I'd back-up inactive projects to another standalone device for safe keeping.
  16. Tesselator macrumors 601


    Jan 9, 2008
    I'm sure you've read the hundreds of discussions on this very topic already discussed here at MR. Most of them end the same with the following points:

    • Backups require less than 10 min. a day.
    • RAID at any level does not negate backing up.
    • All RAIDs need to be backed up!
    • Backups level the playing field making all RAID levels equally safe.
    • The only time RAID0 becomes a detriment is when:
      • You don't have time to wait for a rebuild (~2 hours for 1TB of data)
      • The data is time/mission critical like that of a bank or CC orders, etc.
    • Backup schemes like TimeMachine back everything up immediately negating the above.
    • RAID0 is the fastest and most economical RAID level bar none.

    So all this paranoia and mythology about RAID0 should be gone by now.
  17. Abidubi macrumors 6502

    Feb 13, 2009
    Isn`t that no different from using a single disk, or any sized RAID array? If 1 HD by it's self is in the process of writing a file, then experiences a power failiure, the data is lost as well. Or if a 10000 disk redundant array is in the process of writing the file is still lost. Unless you are talking about a RAID card with a battery backup... but then you are talking about making the RAID array MORE secure than a single disk. Why does he need to care about that kind of thing with a normal backup. His data doesn't need to survive armagedon, just be as safe as it would be without a RAID.

    And RAID 0 with a backup is the best way to go. There is no need for all these other types unless you are running a server. So your array fails, fine. Buy a new HD (cuz you're not going to have a replacement laying around anyway) then when you get it restore from your backup and after a couple hours you'll be good as new.
  18. UltraNEO* macrumors 601


    Jun 16, 2007
    Yep, yep... Surely no-one out there expects to use a RAID array and completely forget about using backup solutions right? Surely no-one out there is that naive or foolish right? I'm sure as hell not.. I back everything up to BluRay, MO disks and external storage in addition to mirroring it to the other MP.

    So for your final point, it makes a great work/project/scratch drive.
  19. johnsonvideo macrumors newbie

    Aug 25, 2009
    RAID card with battery

    Yes, my new RAID card has a battery. So that being said, what is the danger in RAID 5, especially if I have another drive at the ready to insert in case of a drive failure.

    Secondly, anyone care to address my other questions in my post above.

    Thanks again.

  20. UltraNEO* macrumors 601


    Jun 16, 2007
    Even if you have a spare drive at the ready, there's still a slim possibility another drive in the array will or can fail while the array rebuilds the missing data.
  21. nanofrog macrumors G4

    May 6, 2008
    1. A stripe refers to a RAID0 array, which is different than stripe size. Check out the RAID wiki page, if you need clarification. ;)

    2. It's on the logic board, behind the front fan assembly IIRC (left side, top most quadrant).

    3. You should be able to, but the interface may matter on an MP. For example, e SATA could be a problem, depending if it's off the ODD_SATA ports or an eSATA card (needs BIOS boot ROM). If you place it in the empty optical bay, it will work. You do need to install the AHCI drivers in windows though, and then run the drivers of the Boot Camp disk. The partition tool won't be needed, as it's a separate drive.

    BTW, you can build the array from the 3x drives currently available, and then expand the array with the 4th drive when it arrives (do it over night, so it won't interfere with what you need to get done during the time you're awake). I love automation. :D

    I was referring to hardware RAID, but in the case of a bad/failed write (i.e. power outage), the file affected would need to be redone on software RAID, or in the instance the cache is too small to contain the data on hardware RAID as well.

    If running a RAID5, software based methods don't address the write hole issue, so a proper RAID card (NVRAM solution to the write hole) is more a necessity than option. It's just too dangerous IMO, as re performing the task may take a considerable amount of time. Multiple small files can be a nightmare. :(

    A UPS is also a necessity, and does more than the battery for a card. Worst case, if only a UPS or card battery can be used, go for the UPS. Both are highly recommended however. ;)

    Primarily higher redundancy/availability require a different array type, but also the paranoid may see a need for it, especially if the data is priceless, or of a sensitive nature.

    Either way, whether RAID is used or not, a proper backup system is required, not an option if one desires to retain data, and alleviate headaches. :)
  22. johnsonvideo macrumors newbie

    Aug 25, 2009
    RAID 5 and True Redundancy

    Really appreciated your response, nanofrog. Thanks for answering my questions.

    I also appreciated the strong message from others who wrote in these posts about redundancy. Because of these comments, I think I will ask my AutoSave Vault to save video edit files on another external RAID 5. Anyone see any problems with this idea?

    Thanks again, everyone.

  23. UltraNEO* macrumors 601


    Jun 16, 2007
    Having multiple backups can only be a good thing IMO.
  24. johnsonvideo macrumors newbie

    Aug 25, 2009
    Boot Camp and Windows

    By the way, wouldn't it be true that if I'm not concerned about seeing the drives in Windows or Boot camp, I won't need to download the drivers?

    The reason: My Windows XP runs flawlessly using VMWare Fusion, and, therefore, I don't need bootcamp.

    Thanks again.
  25. nanofrog macrumors G4

    May 6, 2008
    :cool: NP. :)

    No, no problem at all. If the data's that important, it's best to have a backup. Or two, or three,... :D :p

    Important data's worth way more than the system, especially if it's paid (contracted) work. ;)

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