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June 12th, 2014 07:00
Driver Space Missing on Dell MD3600i???
Hi All,
i've finally set my dell MD3600i; what i don't understand's i'm using 3 physicals Drivers of 3.725,524GB (11.176,569GB) and 2 of 465,261GB (930.522GB)
I've set it on RAID 5 the 3 disk but i can only see and use 7,451.045 GB and i can see that this space's associated with all thoses disk.
Even when if i set it on RAID 0, it's look like i can use space of one disk.
Thanks for your support
Dev Mgr
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9.3K Posts
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June 15th, 2014 20:00
Raid 1 duplicates 2 disks, so with 2 disks (of 500GB (465GB-ish effectively)), you get 1 disk in usable space.
Raid 5 has a parity drive, which means 1 drive in your raid 5 is lost to parity, which is used in case of a drive failure to reconstruct the data on the missing (failed) drive. So with 3 physical disks (the absolute minimum for raid 5), you get 2 disks in usable space.
So your numbers are exactly what I'd expect to see except that I don't think you checked the disk size correctly when you selected raid 0, as a raid 0 would give you the full space of the smallest drive times the number of drives in the raid 0. Note that raid 0 has zero redundancy, so if you lose 1 drive you lose all data, which is why it's only useful in situations where absolute performance is required at the sacrifice of data availability (and you have a very good backup plan in place or don't care if the data is lost when a drive even just 'glitches').
DELL-Sam L
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June 12th, 2014 12:00
Hello Francis B.,
Since you are using a raid 5 setup the max disk space for the 3 drives would be about 8000GB. Now that number comes for the overhead of the disk themselves. You also have a little bit of overhead for the MD3600i as well & that is where the extra space is going. Now when you select your different raid types it will change the required amount of reserved disk space that is need & that is why you see less space needed for a raid 0.
Please let us know if you have any other questions.