Discussion in 'Mac Pro' started by Hally231, Apr 5, 2011.

  1. Hally231 macrumors member

    Oct 25, 2010
    To start with i had installed a Apple Raid card for my mac and it was installed successfully.

    So my 3 new 2tb hard drives arrives today giving me 8tb in total (4x2tb)
    As my last OS was installed on a 1tb drive that i am going to sell i had to install a fresh copy of leopard on a new 2tb hard drive in bay 1.

    Having done this my mac and RAID profiler only recognised hard drives in bay 1 and bay 2. I searched throughout the system profilers, disk utility etc and no other drives were present. I assumed it had something to do with the raid card so i took it out of the machine and booted the mac up and the other drives popped up!

    After installing snow leopard and updating, my mac is now booting to a blue screen that when i press the power button (sleep) then press any key - the mac boots back up to the home screen but everything is FROZEN!!

    Ive tried inserting the leopard disc and booting from that but it just wont do it! I will try using target disk mode tomorrow with an imac and firewire cable but im just wondering if everything gets installed again and then i install the RAID card back in - will it only see the 2 hard drives again?

    Has anyone else experienced what i have?

    Thanks so much for you time

  2. nanofrog macrumors G4

    May 6, 2008
    Don't panic, this is normal.

    You're seeing the single drive (meant for the OS as I read your post), and the other is the array (n disks in an array = seen by the system as a single disk). Hence why you only see 2 disks.

    A couple of notes:
    1. That particular RAID card is garbage. If you can return it for a refund, then I'd recommend doing so and getting a better card (I and others here can help you out on which make and model).
    2. Keep the OS disk off of the RAID card (= system's SATA ports = ICH; I assume it is, but not entirely sure). The reason for this, is so if something happens to the array, you still have a working OS. Conversely, if the OS disk goes, there's less work to do (only need to restore the OS, ideally from a clone, and you're done). Either way, it saves you time.

    Generally speaking, you cannot use sleep with RAID cards (regardless of the brand of card; there are exceptions here and there, but it's quite uncommon, and the MP running OS X has been proven not to be one of them). The reason for this, is when you put it to sleep, the RAID card's firmware is lost. So when you wake it, the disks are no longer available to the system, and requires a full reboot to get them back online.

    Disable sleep, and shut the system down when you'll be away for more than say 4 hours or so (time frame is up to you).

    The Install disk won't help, as it doesn't load the drivers for a RAID card (why you can't see it).

    And yes, you'll only see 2x disks when the card is up and running (= normal, see above). :)
  3. Hally231, Apr 5, 2011
    Last edited: Apr 6, 2011

    Hally231 thread starter macrumors member

    Oct 25, 2010

    Thanks for the info, how do you create a raid 5 array then if it only shows 2 hard drives as the 5 array option is blanked due to less then 3 hard drives being present?

    So, shall i install leopard again without the RAID card in the system and then ass the RAID card back in?

    Will the RAID then detect the other drives so i can create a raid 5 setup?

  4. initialsBB macrumors 6502a

    Oct 18, 2010
    Wirelessly posted (iPhone: Mozilla/5.0 (iPhone; U; CPU iPhone OS 4_3_1 like Mac OS X; en-us) AppleWebKit/533.17.9 (KHTML, like Gecko) Version/5.0.2 Mobile/8G4 Safari/6533.18.5)

    Why say that the Mac Pro RAID card is junk ? It may not be the highest performance or cheapest solution for a Mac Pro but in certain circumstances it has the advantage that when a problem comes up you can rely on Apple support.

    If it was for my personal Mac Pro on which I do no billed work, only self training, I'd definitely hunt around for a better solution. When I am asked to provide purchasing advice to a company that has no dedicated technician that looks after the computers, I much prefer having them take an Apple card. A 4x2TB drive RAID 5 on the Apple card offers ample performance for most cases (video for my trade).

    >edit> I'll add that very little of the information on the forums around here regarding alternate RAID cards is accessible or clear to non-geeks.
  5. nanofrog macrumors G4

    May 6, 2008
    The way I read the initial post, is that the RAID was good (level 5 array), so it and the OS show up as 2x volumes in the system.

    If this is not the case (seems so at this point), then please elaborate further.

    Let's try to determine if one of the disks you're trying to use is bad or not first (could just need to be reseated or moved to another HDD bay).

    Make sure you turn off the system before trying to move any disks, as the MP does not support Hot Plugging (has to do with inrush current = electrical issue, not software support like Hot Swapping is).

    If all the disks are good and show as available for use (RAID not yet setup & initialized), then you can make a RAID 5 of them.

    Eliminating speed and cost:
    • Battery issues
    • Only works with 1x OS
    • Apple's support for their RAID card sucks (beyond basic in instances where clients had this product). Real problems left the customer unresolved and angry (lost time, and increased frustration).
    Placing cost (value) and performance back in, then you can get a 3rd party card that can offer more ports, improved throughput (even with only 4x disks), additional OS's, and features (particularly for recovery). Specifically, I mean Areca and ATTO, as they both run under OS X and support EFI booting.

    And their tech support actually knows what they're doing = cherry on top. :D

    I realize that it's nice to have a single point of contact, but when it's useless for RAID, I see having a separate point of contact that knows what they're doing and can actually help, being a far superior solution.

    In the case of total newbs to RAID (have no IT support or willing to hire a consultant or part time IT person when needed), I'd go with ATTO. Their products are more expensive than Areca, but they're located in NY, so the support staff speak English as their native language (easier to understand than some of Areca's responses, though accurate, can be more difficult to understand, as they're based in Taiwan).

    RAID is rather confusing, as each solution is custom (can be similar for the same type of usage, but the smallest detail can change things). So a "one size fits all" solution isn't the right way to go (what you might be presented with when getting advice from a company that sells RAID products, particularly if they're the vendor <own/use the same name as the label on the box>). The best thing to do IMO, is hire a storage consultant (don't sell products = no corporate loyalties/personal stake in sales). It costs money, but it will save more in the end by not trying to use the wrong solution to the specific requirements.
  6. Hally231 thread starter macrumors member

    Oct 25, 2010

    Sorry about the poor explanation, anyway i have finally managed to install a clean leopard install on the mac pro WITHOUT the RAID card installed, have updated everything and now installed the RAID card back in the machine.

    Its now showing all the drives i have present so i went ahead with creating a raid 5 array. I have 4x2tb hard drives and of course on bay 1 i have leopard installed. Because of this i selected 3x 2tb hard drives and left the box 'use unassigned drives as spares' unticked as i have my OS installed on the spare drive.

    The RAID gives me 3.92TB of space out of a possible 6TB. Okay here come the questions,

    Whats happened to the other 2.08TB of space?
    If 1 hard drive fails - do i just replace it with a new one after setting it up as a global spare?

    From what i read, i thought i could of had 6tb of RAID 5 space with the 'data strips' being written to my hard drive bay 1 which also has my OS on. That way if 1 of my 3 hard drives fail (6tb) i can replace it with a new one and the 'strips of data' from hard drive bay 1 could then repair the RAID.

    Thanks nanofrog for all your help thus far.
  7. nanofrog macrumors G4

    May 6, 2008
    Glad to hear you've got it up and running.

    As per keeping the boot disk on the RAID card, there's no advantage to it (cache is used for writes only, and an OS disk is primarily used for random access reads).

    So again, I'd recommend getting it off of the RAID card, and attach it to the system's SATA ports (ICH). Specifically, place it in the empty optical bay. There's a couple of reasons (advantages) for doing this.
    1. You get one of the HDD ports back which you can use for either a Hot Spare or leave empty for future expansion (capacity and speed).
    2. Saves time/makes a recovery easier. That is, if the OS goes down, it's easier to just restore the OS via a clone without any risk of user error deleting data on the array (i.e. accidentally delete the array for example). If the card goes down/array dies, you have a working OS (will allow you to boot the system), which can significantly make a recovery easier and faster.
    In terms of capacity, for a RAID 5:
    • usable capacity = (n - 1) * capacity of a single disk (or smallest capacity if the disks are of unequal size).
    So for 6TB Raw capacity (2TB each), the usable capacity = 4TB. The slight difference from 3.92 to 4 is due to how disk makers compute capacity (they use 1GB = 1000 Bytes, not 1024 Bytes).

    As per what to do with a disk, Yes. You pull the bad disk, and replace it with a good one. Set that as a spare, and the card will automatically begin rebuilding the array.

    With a Hot Spare (if you follow the above advice), a good disk is already available, and the rebuild would begin automatically without user interaction (you'd still need to replace the bad disk, and set it as a Hot Spare again to regain this ability).
    No, this is not possible.

    The parity disk must be part of the RAID set, which is why usable capacity is the formula I listed above. A separate disk from the array cannot be used by the disk (not set as a Hot Spare, which is actually part of the set as well).

    :cool: NP. :)

    A couple of other notes/recommendations:
    1. Get a good UPS system if you don't already have one (get one with a pure sine wave inverter, not a stepped unit, as the MP's PSU <Active PFC> can be damaged by these).
    2. Test the array out for failure conditions prior to trusting your data to it (let's you see how it will react and what you need to do to fix it). Helps prevent confusion/mistakes when a real one happens.
  8. Hally231 thread starter macrumors member

    Oct 25, 2010

    Thanks again for your detailed replies - they are much appreciated

    I will most likely get a backup power supply shortly.

    The RAID is still creating the volume (been about 15 hours now) but is about 3/4 complete.

    Why does it take so long?

    I now have the RAID volume disk on my desktop, so once the volume process is completed - do i just drag files/folders onto that volume?

    Will this take longer then usual data transfer?

  9. Riot Nrrrd macrumors regular

    Riot Nrrrd

    Feb 23, 2011
    Lost Androideles
    You don't seem to be listening to nanofrog. Maybe if someone else tells you the same thing, you'll listen. :p

    Get another disk - preferably an SSD - and put it in your (presumably unused) 2nd optical drive bay, possibly via adapter (OWC sells them). Put your OS install on that disk.

    Then you can RAID all 4 of your drive bay disks together via the Apple RAID card.

    I have this exact configuration you do (pending arrival of the SSD/adapter bracket) so I can recommend it just as much as nanofrog did.

    Someday you'll be glad you listened to us. :D
  10. Hally231 thread starter macrumors member

    Oct 25, 2010

    I have taken all what nanofrog has said into consideration its just i had spent £400 (>$800) on the RAID setup so far and its only for personal use - not for business. SSD drives are a lot at the moment but i guess i could have a look into it.
  11. Riot Nrrrd macrumors regular

    Riot Nrrrd

    Feb 23, 2011
    Lost Androideles
    Mine is also for personal use. The separate disk idea (SSD or cheap SATA) is so that you can not only maximize your RAID storage, but also to protect you in case the Apple RAID card dies or otherwise mangles your RAID setup, so you can still boot the machine while attempting repairs/forensics.

    Think about it.
  12. Hally231 thread starter macrumors member

    Oct 25, 2010
    Okay cool, could you tell me how i would connect the SSD drive to the logic board?

    How much are SSD drives these days?
  13. nanofrog macrumors G4

    May 6, 2008
    Proper RAID isn't cheap.

    As per an SSD, it will speed up your boot and application load times (OS/applications rely on random access reads, which SSD's are the fastest non-volatile tech out there ATM).

    Exactly, and it's why I mentioned it as well. ;)

    Now if it were a RAID 1 for the OS, then a card is preferable to a software implementation when possible (i.e. what's done for high availability servers). Most enterprise systems use the ICHxR (RAID version), which includes a simple hardware controller (capable of 0/1/10/5, so it's viable for a RAID 1 via hardware on the cheap). Unfortunately, Apple doesn't use this version (only use ICHx), as they're too cheap. :mad:

    Place it in the empty optical bay (system only comes with one filled, unless you ordered a second optical drive).

    As to the specifics, we don't know which machine you have, and those details matter (primarily cabling). But it's not hard. Once we have this little detail, we can get you pointed in the right direction.

    BTW, are you a DIY type of person, or prefer ready-made solutions?

    Given you're in the UK, is a good source (I send UK clients there for gear). So is OWC (decent SSD's & pricing), but you'd have to ask about shipping and I presume handle payment of the VAT on your own (they do ship internationally, and other UK members have purchased from them in the past).

    You don't need to go huge either.
  14. Hally231 thread starter macrumors member

    Oct 25, 2010
    Well im going to stick with my current RAID setup for the moment especially as SSD are soo expensive.

    Nanofrog - A volume has now been created on my RAID (took about 20 hours)

    Why does it take so long?

    As my RAID battery is dead its not charging and the 'write cache status' gets automatically disabled. I can turn the write cache on but what does this do?

    I have dragged a file onto the RAID volume on my desktop - is that it, is that file now back-upped within the RAID?

  15. Hally231 thread starter macrumors member

    Oct 25, 2010

    UPDATE: Change of plan.

    Okay, i have found a 3.5" ATA 40GB hard drive in an old dell computer which i have connected it as the 2nd optical drive and its all working on my mac.

    To install it properly into the optical drive sled shall i buy this? -

    Right, so i will use the 40gb hard drive as my OS install destination and the other 4x 2tb hard drives for RAID 5 array giving me 6TB of space :)

    What shall i do about my RAID 5 i have set up at the moment?

    Shall i delete the volume and then delete the raid?

    After that, do i need to format the disks?

    Once thats done i should disconnect the RAID card, install fresh leopard on the 40GB drive, update etc and then insert RAID card back in and hopefully thats it!

    Thanks nanofrog in advance - i know you will know what to do ;)

  16. nanofrog macrumors G4

    May 6, 2008
    Generally speaking, Yes in terms of cost per GB.

    But they're coming down. OWC has a 40GB SSD for $100USD for example, and that disk makes a great OS/applications disk or dedicated scratch drive for example (why I mentioned there's no need to go huge).

    In my experience, the $100 USD mark is what most users will accept as disposable for disk technology. The difference with SSD's, is the capacity is smaller.

    That card is slow, and your mention of the battery issue makes matters worse for writes (card's cache does not affect reads at all - it's only used for write performance by allowing the system to off-load the processed data to be written into the card's cache).

    Other cards would have done this much faster (4 hrs or so, as a decent card can initialize ~1TB/hr for RAID 5).

    It improves your write speeds (only used for writes, so it has no effect on reads).

    It's on the array. As it's a RAID 5, it's stored across all the members in 2x forms. One is over the stripes on the active disks, as well as the parity data (what a dead/missing disk is restored from).

    But understand, that RAID does not mean you can skip a backup. No matter how redundant the primary storage pool is, you still need a proper backup system, as things do go wrong (no such thing as fool-proof).

    This mount would work, but as I still don't know the exact model of MP, the cabling is unclear.

    • 2009 on = single connector at each optical bay that contains both power and data.
    • 2006 - 2008 = 4 pin Molex connector and SATA ports (labeled ODD_SATA = unused SATA ports for the Optical bays) on the logic board. So you'd need a Molex to SATA power adapter cable, and a standard SATA data cable and run it from the drive to one of the ODD_SATA ports (more of a PITA than 2009 or newer).

    You don't have to, but it would be faster if you did (requires a backup system with a complete copy of your data).

    RAID cards are capable of something called Online Expansion (allows you to add a disk without loosing any data on the array). It's slower than just initialization, and in your case, would be affected if the write cache is Disabled. It's risky to turn in on without a proper UPS system, but that's your decision (i.e. I've no idea how stable your power is).

    The best way IMO, is the following:
    1. Install the OS/Applications disk (remember, OWC sells a 40GB SSD for $100 USD, and that old 40GB disk is going to be beyond slow, particularly for random access).
    2. Clone the existing OS and applications to the new disk.
    3. Make the existing OS disk available to the array.
    4. Use Online Expansion to increase the RAID's capacity (additional members also give a speed improvement up to the card's limit).
  17. Hally231 thread starter macrumors member

    Oct 25, 2010
    To clone the existing OS etc shall i use a program like SuperDuper and how will i change it so the hard drive connected in the optical bay will be the drive to boot from at startup (primary drive)?

    When i delete the volume and RAID will the single RAID volume separate back into the 3 2TB hard drives?

    Thanks Nanofrog!
  18. nanofrog macrumors G4

    May 6, 2008
    You can use Super Duper if you wish. Carbon Copy Cloner is another one that many like (even disk utility will clone).

    Once the clone is made, you go into Disk Utility, and set the new disk as the boot location.

  19. Hally231 thread starter macrumors member

    Oct 25, 2010

    Okay i have 'cloned' the hard drive using disk utility but don't know how to set the new disk boot location - could you help me please?

  20. nanofrog macrumors G4

    May 6, 2008
    1. Go into System Preferences
    2. Go into the Startup Disk icon (it will list your available drives)
    3. Select the drive you want to boot from
    4. Restart
    This will get you sorted. ;)

    Sorry about the confusion (so much is under Disk Utility, I listed it by mistake).
  21. Hally231 thread starter macrumors member

    Oct 25, 2010


    All done - thanks to you!

    Just creating the RAID volume now - should be done in 20 hours or so.

    Nanofrog you have been a great help.

    Peace x
  22. nanofrog macrumors G4

    May 6, 2008
    :cool: NP. :)

    Now you want to get a good UPS as soon as possible, and test it out under failure conditions (before trusting important data to it - just duplicate existing data from a backup or create something you don't actually need for test data = if lost, it won't hurt you). ;)

    Also, once you have the UPS, Enable Write Cache on the card, and that will speed up writes for you (new battery would allow this as well, but the UPS is a better solution when only running one or the other).

    Good luck. :D
  23. MacInMotion macrumors newbie

    Feb 24, 2008
    Please expand on recommended RAID cards

    Nanofrog, I have some questions.

    First, let me say that I have a 2008 Mac Pro with the original Mac Pro Raid card. At the time it was a great solution because not only was it an Apple-supported bootable RAID card, I could also put SAS drives in it. SAS drives are much higher performance, particularly for an OS drive, than SATA drives. So that was an all around win: OS on the SAS drive, data on the RAID 5.

    Now, however, I agree it would be good to do things differently. For one, this RAID card is dangerously slow to do a rebuild. Last time my 4TB (3 x 2TB drives) RAID 5 array lost a disk, it took 70 hours to rebuild. Almost 3 days. Insane.

    For two, for some reason the RAID card usually reports that the shutdown was disorderly, meaning it didn't get to finish writing to the drives before the power went out, which means it is very dependent on its built-in battery. Of course, the battery is custom Apple stuff and Apple will not replace it, they will only sell you a new card (already had this one replaced once under warranty). So now I'm getting worried about what happens when this battery gives up.

    This is the single-point failure mode people often overlook with RAID. If your RAID controller goes out and you cannot replace it with an identical controller, you've lost your disks. With my setup, I can only use a 2008 vintage Mac Pro with the 2008 vintage RAID card to read the array. Eeew.

    For three, you are right, Apple's support sucks. They clearly do not care about this product and are only moving further and further away from heavy-duty computing.

    I've been sticking with it, though, on the grounds that the SAS drive was hard to beat, this card was the only thing that would boot off the SAS drive, and this card was one of the few that would use the internal drive bays.

    However, now that I'm on my third RAID rebuild of the year (one drive had infrequent failures, finally replacing it) and OWC has their Mercury EXTREME Pro 6G SSD with 5 year warranty at $200 for 120GB, I can dump the whole thing. The new setup will be the bootable SSD in the optical drive bay with the on-board SATA and 3 SATA drives (non-bootable) on the RAID card, and eSATA drives for booting to other OS's. (I shift around between 10.5, 10.6, 10.7, and when it comes out, 10.8 as well as wanting to reserve the capability to boot into Windows. I'm not stuffing all that into one SSD.)

    So my big question is what to use for an internal RAID card. The ATTO cards look to be over $1,000, the Areca $700, and none of the cards I looked at from any vendor look like they'll reach the mini-SAS cable inside the Mac Pro chassis. (I'm sure I can get a mini-SAS cable extender but I'm worried about cable length. Those internal SATA cables really have trouble at 1 meter.) Do I really need to spend that much? Newer has their MAXPower RAID and Highpoint has their RocketRAID and I'm sure there are others that are less than half the price of the Areca. What am I really getting for the extra money?

    If I don't need to boot off the card, can you recommend a less expensive manufacturer?

    Next question is about on-card batteries. The ATTO card does not seem to have a battery or an option for one. The Areca has an option for one. Are they doing something else to recover from a power loss or do I need to get a battery? I have a UPS but the fact that my Apple RAID card keeps complaining about a disorderly shutdown makes me worry that the system is removing power before the writes complete and the UPS is not going to help there.

    Thanks for your advice!
  24. nanofrog macrumors G4

    May 6, 2008
    Ancient Thread!!! :p

    SAS did, and still does have it's place. But it's horribly expensive.

    Fortunately, SATA can fill in the void where SAS isn't absolutely necessary, and do so at a lower cost, such as a stand-alone small business or home system. I suspect this is where you come in, unless you're trying to salvage your existing drives (I do see you're interested in a newer card).

    SATA based SSD's can outperform SAS based mechanical disks as well, so SAS may not have a performance edge, even when compared to the fastest spindle speeds available.

    Without further specifics though, I can't really be certain if switching to SATA is the right move for you or not. Certainly cheaper, but if it's running an absolutely critical system, then SAS may be the better choice (i.e. must have as close to 100% uptime over the system's entire lifespan).

    You're not wrong, but in most cases, there are financial restrictions that have to be balanced.

    So taking failure statistics into account, you'll find that the RAID card is far less likely to die than a disk, which helps tremendously for many users (those that can't afford to have multiple cards with identical arrays, and then repeat the entire system for a true n=1 or better redundancy level <entire system dies, another takes over it's job immediately>; this sort of implementation does exist, but isn't common but for critical systems within companies that can't afford not to do this - think banking data for example). It even gets more extreme... (think multiple facilities that contain identical systems and data but located in different parts of the planet to avoid total loss in the event of a natural disaster).

    They're it in terms of proper RAID cards that work in a MP. LSI *might* have a model that would work after being hacked, but I wouldn't go that route. Too risky IMHO.

    Such a product is available, and works (been done before).

    MAXPower is just an RoC IIRC (what do you expect for under $300?), not a full fledged RAID card, and Highpoint is something to avoid like the proverbial plague due to support as bad or worse than Apple's (horrible stories in here by users that tried a Highpoint; couldn't get firmware or drivers for example). :eek:

    As per the cards from Areca and ATTO being as expensive as you're seeing, it depends on exactly what you need. They do offer suitable cards for less money if you don't need high port counts or perhaps the latest models (not enough details to be sure what to recommend yet, though it seems as if a 4 - 8 port card is all you'll need at most).

    The extra funds spent on an ATTO or Areca get you real support, better features (in terms of ability to recover a failure), and better performance. So it's not a waste.

    Personally, I recommend 4 more ports than you need now, as it makes the first round of expansion cheaper (just add more disks) vs. replacing all of the disks every single time. Much cheaper in the long run.

    Card batteries are nice, but the UPS is far more important, which is why ATTO seems to no longer make card batteries available (lack of sales, as educated buyers know this, and have backup power systems we'd both drool over; UPS + generator system that's also redundant).

    Worst case, the existing data is still there, but a process that was lost due to say loss of power on the UPS, would have to be repeated.

    There are additional features in cards such as ATTO and Areca. For example, they keep a copy of the partition tables stored on their ROM's in the event the PT's are wiped out from the disks.

    As per the Apple card issue you describe, it's particular to that card (i.e. card battery isn't able to maintain a charge, thus it logs an error when the charge isn't detected). Even though the system is fine (assuming this is the case, as you'd have had all kinds of hell in the form of data rebuilds every single time you turn on the system).
  25. MacInMotion macrumors newbie

    Feb 24, 2008
    Re: Please expand on recommended RAID cards

    Yes, nanofrog, this is an ancient thread, resurrected through the power of Google. :)

    Thank you for giving us the benefit of your wisdom and experience!

    I'll fill in the details you asked about. The Mac in question is the office workhorse, doing everything from film editing to media transcoding to file serving to hosting virtual machines. It's on 24x5 [sic] and already has the SAS drive and SATA drives, so I'm not switching, I was just explaining why it has 1 SAS drive and 3 SATA drives. Now the SSDs have better cost/performance than the SAS drive, so I can switch. It's for work and it's important enough that I want to do it right, but I want to be economical about it, too, which is why I'm still nursing a 4 year old machine.

    The SATA drives have enough performance for everything but the virtual machines, where synchronous disc writes to a SATA based RAID 5 array kill the Mac Pro RAID card, paralyzing the system. We can live with it, though, by using the SAS drive judiciously. Anyway, SATA RAID is all we can afford given the amount of storage we need and the requirement to maintain 100% availability. (We'd need better than hourly incremental backups to maintain freshness and could not handle the downtime of restoring from one if a disk went out. With RAID we can get away with weekly incremental backups plus hourly for just the "hot" files.)

    My question about on-card batteries was not about power failures but rather about emergency power-off (press and hold the power button until the Mac powers down) or similar scenarios when the Mac hardware turns off without proper shutdown procedures. The Apple card's battery ensures that it can flush writes to disk when power is restored. As you know, with a RAID 5 or 6 setup, it's obviously not sufficient to have file system journaling, you need to ensure all the parity stripes are updated, too. How do the ATTO and Areca cards handle this without a battery?

    The $700 Areca card is more than I need with 8-ports but I did not find a 4-port internal version. My plan for expansion was to get a QNAP NAS server (probably the TS-659 Pro II) as not all that much more expensive than an external drive enclosure and use that for our file server, freeing up our Mac from that and other tasks while also letting us migrate to RAID 6.

    So really a drop-in replacement for the Mac Pro RAID card is all we need: 4 internal ports, SATA only would be OK but SATA/SAS would be better. If we can get a new card that fixes the VM bottleneck, that would be great, but it's not a requirement. I was thinking more like $450 would be the right price, but I've already spent $700 of time researching it. :) Still, for the 'net, pleas post your recommendation.

    And if you have advice about the QNAP, please go ahead and throw that in, too.

    Thanks again.

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