July 7, 201115 yr I'm a bit of a Noobie to Unraid. I have everything setup and working, but for some reason none of the data on my arrays is writing across the drives in the array. I have the shares setup to split level 2. My structure is something like this: iTunes [user share] iTunes Music Movies Pictures [user share] 40th B-day Cruise Rylin B-day pics etc. Box_Office_Movies [user share] Gladiator [2004] Video_ts Superman [2000] Video_ts etc.. After moving my iTunes library and burning several movies to the array, I noticed that the files don't show up on any disk but disk 1. So, I tried creating a test share with split level 0 and I added a folder and a few files to the folder. These also did not show up on any other disk in the array. BTW... I have all of the share setup for highwater. I have two questions that I'm hoping someone more technically competent with unraid than I can answer: 1. Why is the data not spanning the available drives at each write? 2. Now that all the data is on a single drive, is there anyway to make it span after the fact? Or, do I have to completely remove and rewrite it all? I'm hoping not... I appreciate any ideas anyone has that might help! My syslog is attached. unraid_syslog.txt
July 7, 201115 yr Let's see if I can get this right. A share's allocation method determines when/if unRAID moves to the next available drive when writing files. Using High-water means the share's first drive will be used until available space is half used, and so on, in turn, then back to the first when all are half full. If you want the drive with the most available space to be used for every file copied then you want Most-free instead of High-water. Most-free would be the closest to traditional RAID, sort of. This still won't guarantee writes are distributed, say when you've deleted more from one drive than others, but the real downsides are this will almost guarantee reads and writes of more than one file will need to spin-up multiple drives which takes longer and consumes more power. Versus traditional RAID, typically using all available resources for optimal speed, unRAID works to consolidate files as long as it can and minimize power utilization.
July 7, 201115 yr ^ Correct. Versus traditional RAID, typically using all available resources for optimal speed, unRAID works to consolidate files as long as it can and minimize power utilization. That is a very concise way to explain High-water, I like it. I might have to steal that line from you lanceg321: You don't have anything to worry about, unRAID is behaving as it should. High-water is designed to minimize unnecessary spin-ups, so from that perspective it is actually a good thing that your data is not spanning drives. If your disk1 gets over half full and your data is still not being written to the other disks then that could indicate a problem, but at the moment I don't see anything wrong with what you've described. By the way, unless you have some reason why you want your data spread out as much as possible, I recommend sticking with High-water.
July 7, 201115 yr Author Ah... I understand now. I didn't realize that high water waited until the initial drive is half full before distributing the files. I am only about 20% full on the first drive so this does make sense. I really appreciate the explanation guys! I was concerned that I don't have the same level of protection if all of my data was on one drive vs. multiple drives. This is very likely just my lack of understanding on how unraid works with parity. Either way... I feel MUCH better about it now and will continue fleshing out my media library! Thank you for the responses.
July 7, 201115 yr Every data disk in your unRAID array is equally protected, spreading out your files will do nothing to add more protection. The only way to gain more protection is to duplicate your files across different disks. For example, I have a user share called 'Backups' that is only on disk1 (I specified this using the included/excluded disks settings for that share). I have another identical share called 'Backups (Mirror)' that is only on disk2. I manually drag and drop the contents of 'Backups' into 'Backups (Mirror)' every couple of weeks. This ensures that all data in 'Backups' is duplicated on two disks, which mitigates the chances of losing that data in a catastrophic failure (meaning 2 or more disks failing at the same time). For absolutely critical data, I also use Crashplan and Wuala to gain free off-site backup. If you are truly paranoid you could use my above method to duplicate your critical files across every single data disk in your server. This means that your chances of losing data due to multiple simultaneous disk failures is close to zero. However, I figure that if 3 or more disks are failing at once then the failures are likely due to some external factor such as fire or flood, so the whole server is likely to be toast. unRAID makes a great first line local backup device, but true backups must be duplicated off-site as well.
July 7, 201115 yr FYI, high water is not as simple as just filling until the disk is 1/2 full. http://lime-technology.com/wiki/index.php?title=Un-Official_UnRAID_Manual#High_Water Peter
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