Question on Drobo - extending partitions

Discussion in 'Buying Tips and Advice' started by salmacis, Jul 23, 2008.

  1. salmacis macrumors member

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    #1
    Hi!

    Initially I wanted to post this to drobospace.com but there you need a Drobo serial # for posting/reading (very strange...) - so if there are some Drobo users that can shed some light here...

    Well, I'm planning to buy a new FW800 Drobo but have one remaining question:
    If I plug in 3 x 1TB disks (to have a net total of 1.8 TB available) and partition the space into 2 equal sized ones, i.e. 900MB each (one for time machine, one for other stuff). What happens when I add 4th 1TB disk - which partition is enlarged then? Can I choose or even distribute the additional space? (I would go for a 4TB volume size, that is possible on the new drobo...)

    Didnt find anything in the manuals.

    Thanks,
    salmacis
     
  2. stomer macrumors 6502a

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    #2
    I don't have a Drobo, but I'm interested to know what the answer is to your question.

    I would have imagined that the available storage would be increased but it'd be up to the user to resize the partitions.

    I'm considering using ZFS on my future Drobo, which, I think, would make using any extra storage a breeze.
     
  3. markos1 macrumors newbie

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    #3
    Drobo supports "thin provisioning" which is used in a lot of ultra-high-end enterprise SAN environments. This way it would work is this (I'm not an expert but I'm pretty sure this is right; someone can correct me otherwise):

    - you would add your 3x1TB to get 1.8TB of usable space.
    - But when you create your partitions, the Drobo will tell your filesystem that each partition has the maximum allowable space (16TB in HFS+ or Vista NTFS; 2TB in some older filesystems like pre-Vista NTFS if you wanted that for a Windows partition that was XP compatible).
    - So rather than 2x900MB partitions that you have to decide in advance, you get 2x"16TB" partitions from the very beginning as far as your OS is concerned. There is never a need to expand a partition.
    - The actual space on the Drobo is shared dynamically between them so you can store 900MB+900MB on or 300MB+1.5TB without running out of space. You don't have to decide in advance how you want to use the partitions.
    - Once you do get close to the 1.8TB real limit, the Drobo would warn you to add more space and, again, that new 1TB of space would be shared among the partitions.

    For the other commentor: ZFS has thin provisioning, too, through its notion of a storage pool. But ZFS is not currently compatible with Drobo. The nice thing about Drobo is that it brings essentially all of the nice features of ZFS to HFS+, NTFS, FAT32, or ext3 so you don't have to wait around for an implementation on your OS and don't have to worry about backward compatibility with legacy machine you may have.
     
  4. stomer macrumors 6502a

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    #4
    Argh. That sucks :( Does that also mean that you can't format the thing with ext3, reiserFS or NTFS?

    Almost, the Drobo can't do snapshots can it?
     
  5. markos1 macrumors newbie

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    #5
    It can do ext3 and NTFS but not ReiserFS (currently... who knows what they may add in firmware updates since originally ext3 wasn't included). I don't think it does snapshots so people tend to use things like Time Machine for that. No question that ZFS is great technology that may eventually mitigate the usefulness of a Drobo for Mac and Solaris users (it is unlikely to ever come to Windows or to Linux in any real form due to licensing issues) but for what Drobo is today, it's pretty awesome IMHO. And hopefully they'll keep innovating to add neat features.
     
  6. stomer macrumors 6502a

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    #6
    I don't see the Drobo and ZFS necessarily as competing technologies or even mutually exclusive.

    The Drobo can do some things that ZFS can't and vice versa.

    1. The Drobo provides a nice piece of hardware that allows you to add/remove hard disks at your leisure, ZFS on its own doesn't do this.

    2. RaidZ isn't as flexible as what the Drobo provides. Once you've created your RaidZ array, you can't expand it. Lets say you want to add an additional disk, you've need to destroy then recreate your RaidZ. You could just add the disk to the same zpool that the RaidZ belongs to but then you lose redundancy. In order to preserve redundancy, you'd need to purchase an additional disk or disks and create a mirror or an additional RaidZ. This is a big pain. The Drobo handles additional storage very nicely.

    3. Since you can't format the Drobo with ZFS, you can't have snapshots. ZFS snapshots are way better than what Time Machine does.

    I'm seriously considering purchasing one. The ability to add remove drives, and increase storage over time is a killer feature. My only concern is about the unit itself, what if it fails? What if the Drobo's logic board melts? What happens to your data then? Buy a new Drobo? I think this is a situation where software based raid wins over hardware based raid.
     
  7. RedTomato macrumors 68040

    RedTomato

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    #7
    I don't have a drobo, but I find them interesting devices, so I know a bit about them.

    You lose the size of the largest disk. So 3 x 1 TB will give you 2TB storage. (which might or might not be the same as the 1.8TB you mentioned after shrinkage)

    4x 1TB will give you 3 TB of storage. However, I've heard that the Drobo has a max partition size of 2TB. So you'd be presented with 2 virtual drives, 1 of 2TB and the other of 1TB.

    If somehow in the future you put in 4 x 4TB real drives, I think you'd get 12 TB presented as 6 drives of 2TB each.

    Back to your 4th drive addition- I think that the virtual disk presented to your OS is enlarged in size (up to 2TB then an additional virtual disk is presented.) It's then up to you what you want to do with the partitions on these virtual drives - if you know a way to enlarge them non-destructively, then go ahead (this can be tricky on some filesystems).
     
  8. tloverro macrumors newbie

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    #8
    Drobo

    Hey, guys! I couldn't help but notice this thread. I work for Data Robotics, makers of the Drobo.

    Just to clear something up straightaway. Drobo DOES support volume sizes greater than 2TB. In fact, since January 2008 we've supported 16TB single volumes for OS X HFS+ and NTFS on Vista. That 16TB limit isn't even a hard limit--that's an OS / file system limit at this point. Windows XP and EXT3 have their own limits at 2TB.

    Additionally, in terms of file systems Drobo supports HFS+, NTFS, FAT32, EXT3 and could potentially support any other file system in the future (I really see it as a matter of demand).

    Also, regarding ZFS...:)...ZFS is wonderful, wonderful like a unicorn. It's really not complete and hasn't been widely deployed outside of test environments. Just try Googling a ZFS review and you won't fin many/any real world reviews. But beyond that...the real issue with ZFS is that at its base it just relies on regular old RAID. Also ZFS is complex--I have a 200 page document on my desk here that is just page after page of terminal commands. On the other hand, we spent years making Drobo simple to use. Our instruction manual is basically just 5 lines of text long.

    If you have two partitions and you add a another hard drive. The storage doesn't get "hard" allocated to either pool. It will be available to whichever pool needs it.
     
  9. stomer macrumors 6502a

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    #9
    Thanks for taking the time to reply here.

    What does 'support' actually mean? I was under the initial impression that the Drobo would act like a single storage device (as far as the OS is concerned), and that I'd be able to use any FS? From what you've said, in order for me to format the device using UFS or ZFS, Drobo would have to have support enabled in the firmware? Or does 'support' simply mean, that formatting in UFS or ZFS should work, but you're on your own if you choose to use unsupported FSs?

    If support needs to be built-in to the device's firmware, then why is this? Is it because Drobo does some on-the-fly partition resizing when the storage space is increased?


    Personally, I was never considering using RaidZ with the Drobo. The Drobo provides the redundancy, I wanted ZFS for its snapshot capability.

    As for ZFS being complex, let the user decide. Personally, I don't find 'zpool create drobopool /dev/drobo' that complex.
     
  10. RedTomato macrumors 68040

    RedTomato

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    #10
    Tloverro,

    Many thanks for responding.

    Ah that must be where I made the mistake. So XP and EXT3 force large storage pools to be presented as a series of 2TB drives. OSX HFS+ and Vista NTFS can deal with drives of up to 16TB. Thanks for the clarification.

    If I had 10 quid for every time someone's asked me about ZFS, I'd be well on the way to having a Drobo of my own now ... I agree with you - until ZFS is successfully used in a production system by a major company for over ooh, a year, stay well away from using it for any business data or anything you don't want to lose.

    There's a slight user issue there (nothing to do with Drobo) in that it can be quite difficult to resize an OSX partition without having to erase it and make a new partition. Tools exist, e.g. iPartition but they're either non-free or require some work in Terminal.
     
  11. salmacis thread starter macrumors member

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    #11
    Does this mean I cannot restrict the size of a partition then (as markos1 mentioned that space is dynamically "shared" between partitions)? Because that's what I want to do here, i.e. restricting Time Machine to a certain amount of space used, because otherwise it would eat away all the storage on my Drobo unless I have enough other things stored there. Or did I get something wrong?

    BTW, creating 2 partitions is recommended for using Drobo with Time Machine (as described on drobo.com), so I'm a bit confused now. How does that work in practice?

    Thanks,
    salmacis
     
  12. sushi Moderator emeritus

    sushi

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    #12
    Thank you so much for your input. :)
     
  13. .mark. macrumors 6502

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    #13
    yeh, that would be useless because you need to set a limit of TM. My understanding of how drobo works is:
    1. When you first set up drobo, you set the maximum size tofor your storage pool. This should be the enough to accomodate your future needs.
    2. if you're only ever gona have 4tb drives in it then set it to 4tb. But if you want room to expand in the future then 16tb. The bigger this is set to though can have adverse affects such as longer times to mount the drive.
    3. once you have set this storage pool size, from within disk utility, you can partition you 16tb drive as 500gb/rest and use 500gb for TM.
    4. then as you fill the 500gb partition up, drobo carries on fine as there is not problem with the drobo becoming full

    I'm probably wrong, but I asked this question on the drobo forums before you required a serial no to access it and from memory it's something like this. can the guy who works for DR can either back me up or shoot me down.
     
  14. mtk75 macrumors newbie

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    Feb 15, 2008
    #14
    I have a Drobo 1, so I don't know if this will apply to the Drobo 2 or not.

    That said, I will attempt to answer some of the questions as best I understand them from the research I've done.

    When I partitioned my drive, it came up as a 2 TB unit. I currently have 2x1TB drives in the Drobo, so it really only has ~1TB of space. The partitioning tool thinks it's a 2 TB drive though. (The manual states that this is a limit of USB2...) My thought is that the firewire drive will come up in the partitioning tool as a drive of the maximum size supported by OS/fw/computer. You then partition that space into the drives you want.

    In my case, that means I now have a 256 GB time machine partition, and a 1.7 TB data partition. I am certain that the time machine partition will fill up first, so the data partition will be the one to expand when I add another drive in the future.

    Going into file systems, the Drobo's firmware matters. This is because the Drobo does not treat the backup of your data like a raid disk! Only actual data in your filesystem is redundant. The Drobo does not need defragging, or other maintenance, because it is handled internally. The data is moved and optimized for retrieval, and backup. When you put a new drive in the Drobo, the amount of time that the system takes to re-allocate data, properly protect all the drives, and add the new space to your available disk space depends on the amount of *data* that the drive is currently holding. In a raid system, the amount of time is dependent on the size of the disk. Because Drobo is aware of where your data resides, it only needs to deal with those areas. It doesn't need to deal with areas where no data resides.

    This difference is also why the file system matters. In order to be data aware, Drobo needs to understand how the file system itself stores and allocates resources. Thus the limitations on the file system types that the Drobo supports. It is not just a dumb disk controller.

    BTW, if the guy who works for DR comes back, I'm a EE with a firmware/software background. DR looks like a neat company which is doing cool stuff. Are you hiring? ;) Send me a PM.

    -Matt
     
  15. tloverro macrumors newbie

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    #15
    In terms of file systems, unsupported file systems will not work. We need to build the intelligence into our device so that they can understand each file system’s unique characteristics. We’re a block-level system so understanding each file system is absolutely critical as it enables our magic. We can always add additional file systems support to firmware over time as we see demand.

    In terms of partitions, yes unfortunately I’ve personally been struggling with the inability to natively expand a partition since the DOS FAT16 days. That issue still exists with modern file systems like NTFS and HFS+. That's obviously an FS / OS issue and that's why we're so proud of our thin provisioning technology.

    In terms of Time Machine, you can partition Drobo so that you may restrict Time Machine's size. As Time Machine approaches filling up the partition allocated to it on Drobo, Time Machine will do it's thing where it starts deleting old files. We also have an Automator action in Alpha that we're testing that would allow you to restrict how much space Time Machine will take up without the need for partitions (it tells TM to use a SparseBundle only up to a certain size).

    Drobo 1 and 2 will work the same.

    We are hiring! Check out http://www.drobo.com/Company/Jobs.html

    if there are any additional questions, please let me know!
     
  16. salmacis thread starter macrumors member

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    #16
    Hi all,

    Thanks for all your posts! Well, it seems that the basic logic with extending partitions is to enlarge the "virtual one", i.e. the one that actually does not have the physical space it represents, right?

    But what about following example:

    Provided I have 3x1TB disks with a net total of 1.8GB, partitioned into partition A (900GB) and partition B (the "rest", which is dependent on the virtual pool size as far I've understood it). What happens, when partition A remains empty and I put 1.5TB of data onto partition B? To my logic, only 300GB remain to be used on partition A, right? Does this mean, I cannot "reserve space" at all? So what's the point to partitioning a Drobo then?

    Thanks again,
    salmacis
     
  17. salmacis thread starter macrumors member

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    #17
    If anyone is interested: I just bought a Drobo (2nd Gen) and it seems to behave as described above: You cannot really "reserve" space on the Drobo by partitioning it, you just set an upper bound, for e.g. Time Machine. In the end not a big deal, just need to pay attention to the space left and in case it is running out, pop in a new (or larger) disk.

    So far I'm satisfied with the Drobo, though it behaved a bit strange on restarting it (needed to wait at least 10 minutes before restarting it, otherwise it went to a reboot loop...).

    Bye
    salmacis
     
  18. Mattww macrumors 6502

    Mattww

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    #18
    I am looking a moving to a Mac Pro shortly and was considering a drobo for my backup needs due to the ability to expand the capacity. I am hoping existing users will be able to answer a few questions.

    With my current G5 I have a 750GB internal drive and backup to an external FW800 drive of the same size with Time machine. I tend to unmount the drive when not in use and power it down. This means that backups don't cause problem with performance.

    With the Mac Pro having 4 drive bays I was considering having a small boot drive and then a 1 or 1.5TB drive for my files and media. If I connect drobo with FireWire 800 can I unmount it and power it down when not in use? I imagine it is designed for 24/7 operation but as it would be in a bedroom I wouldn't really want the drives spinning all the time.

    Does Drobo just use the built-in drivers in Mac OS X? I tend to upgrade my operating system as updates appear so I'd rather not have to wait for software drivers.
     
  19. salmacis thread starter macrumors member

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    #19
    Yes, you can unmount the Drobo, of course. There is also a dedicated app called Drobo Dashboard that allows you to put the whole unit into standby (fan and disks are off). To really turn off the Drobo you need to pull the plug, however (no power switch).

    Regarding noise, the drives are not a problem (well, I use those low power Western Digital Green Drives, barely noticeable), but the fan frequently turns on - not really annoying but not something for the bedroom IMHO.

    Yes, no drivers needed. You even get a fancy icon :)
     
  20. stomer macrumors 6502a

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    #20
    Even when your Mac Pro is running, the Drobo will spin down the drives when they aren't in use.
    This is a great feature as a lot of single drive enclosures aren't intelligent enough to do this.
     
  21. stomer macrumors 6502a

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    #21
    @salmacis

    How did you get on with the partitioning? Did you create 500GB and 1.5TB partitions? You've not noticed any major degradation in performance when accessing the 1.5TB partition whilst Time Machine is performing a backup?

    At the moment I have a separate drive for TM backups, but I'm considering making that drive redundant and reformatting my Drobo with a 500GB partition reserved for TM. But I don't want to do this if it'll significantly degrade file access performance.
     
  22. tloverro macrumors newbie

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    #22
    Better than Partitioning on a Drobo

    Check out Time Tamer which a DroboApp which allows you to set an upper bound for Time Machine on a Drobo or any other storage device with the need for partitioning. I am using it on my Drobo at home and at the office.

    http://drobo.com/droboapps/downloads/index.php?id=16
     
  23. salmacis thread starter macrumors member

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    #23
    However, the fan might be still running even if the drives are off... And the fan sometimes runs even when the Mac is sleeping (not very intelligent IMHO)
     
  24. salmacis thread starter macrumors member

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    #24
    As the virtual pool size on my Drobo is set to 8GB, I made a 1TB partition for Time Machine and a 7GB for the rest (currently I have 3x1GB disks in the Drobo, i.e. 1.8TB usable space). Concerning performance: I can't help you on that, as I don't have activated TM on the Drobo yet (still using another HDD), but will be switching soon. Read/write speeds are generally decent on the Drobo, so I expect similar results as with other external disks though. But in general, if you're looking for top-performance the Drobo may not be the best choice...
     
  25. bestthereis27 macrumors member

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    #25
    I was searching on Drobo and Time machine and found this thread. I am a bit confused on Drobo and Time machine.

    Not sure how to word this so i will try my best. Here is my scenario. I plan on getting a Mac Pro I want to load up 2 additional hard drives along with my normal boot drive. The additional drives will store all my dvds that are handbraked for apple tv. I want a drobo loaded with a couple of hard drives as a time machine. I want the drobo time machine to back up everything on all the drives on the Mac Pro.

    All I want is my Drobo to do is backup with time machine, no extra partitions for anything else. Please explain to me how i can use a drobo to do this. When i first set up do i set the partition to 16TB (assuming my TM will grow over time)? When really I would only have (2) 1.5 TB disk in the Drobo. So if the partition is set to 16TB does time machine think there will be 16TB when i will only have 1.5TB to start? When I start adding additional drives into the drobo with the 16TB drive partition i set earlier will TM just grow into more space from 1.5 to 2 to 3TB etc...?

    So basically can Drobo Time machine backup everything on my mac pro and grow on the fly as more data is filled on the Mac Pro?

    Thanks hopefully that made some sense.
     

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