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Let's get this clear right at the start, I manage servers for a living and I understand RAID arrays and storage pretty well. i know the differences between RAID 0,1,5,6,10,50, etc.
In playing with Storage Spaces on Windows 8 and using a resiliency type of parity has left me confused as to how the drives are filling up as fast as what they are.
In my lab, I created a Windows 8 VM, with 3 x 4GB additional drives. So, 12GB of RAW capacity between the 3 drives.
CREATING THE STORAGE POOL
So, I created a Storage Pool using all 3 drives and am left with a total pool capacity of 9.75GB. It seems that about 750MB of each physical drive is consumed by overhead, leaving me with actual usable space of 3.25GB per drive.
CREATING THE STORAGE SPACE WITH PARITY
So, I created a single space, used Parity for the resiliency type. I set the size to 6GB, so that including the parity information, only 9GB would be consumed. Thus, I'm not using "thin provisioning", but instead ensuring that I have enough capacity to actually store my data.
A LOOK AT THE POOL AND SPACE WHEN DRIVE IS EMPTY
My confusion starts here. Even though I'm not yet storing a single file, approx 35% of my pool is being used. So, considering it's parity, and RAID (Raid 3 specifically from what I have read), I have to assume that it's just visually showing me that 1 out of my 3 drives will be used for parity, and thus nearly 33% will be consumed by parity.
COPY A SINGLE 1GB FILE TO MY NEW STORAGE SPACE
So, I copy in 1 single 1GB ISO file and place it into my Storage Space.
A look at my storage pool, leaves me confused. My pool usage went from 3.50GB used to 5.75GB used because of 1 single 1GB file????? If it wrote say 500MB to 1 drive, and 500MB to a 2nd drive, and consumed 500MB in parity on a 3rd drive...that would be 1.5GB....so I'm unsure how 2.25GB of space was reportedly used.
COPY A FEW MORE FILES TO THE STORAGE SPACE (Approx 4GB worth)
So, I copy some more files into my Storage Space. It's 7 files and totals 4GB of space
Here is the Properties of my Storage Space drive in Explorer;
Explorer looks right, approx 1.8GB free out of my 6GB volume (after copying in 4GB of files)
However, my Storage Pool is pretty much full. Huh? How can this be, I've only copied 4GB of files into a 6GB volume. How can it possibly be out of space??
Summary
3 x 4GB setup would provide 12GB of RAW space (say, if I did RAID 0)
With standard RAID 5 on a server, I would expect 2 x 4GB or so usable (around 8GB), with 4GB dedicated to parity
With Windows 8 Storage Spaces, I setup 6GB for what I thought would be "usable", leaving 3GB for parity and leaving around .75GB still free in the pool.
But yet, after copying 4GB of data, I'm maxed out. And trying to copy any more data to my Storage Space takes the Space "OFFLINE" as it's full.
So, it seems 4GB out of 12GB is usuable. So, it's 33% data, and 66% parity and overhead. How can this be this inefficient? A parity setup should provide more "usable" space than a 2-way mirror....which would give me 50%.
In playing with Storage Spaces on Windows 8 and using a resiliency type of parity has left me confused as to how the drives are filling up as fast as what they are.
In my lab, I created a Windows 8 VM, with 3 x 4GB additional drives. So, 12GB of RAW capacity between the 3 drives.
CREATING THE STORAGE POOL
So, I created a Storage Pool using all 3 drives and am left with a total pool capacity of 9.75GB. It seems that about 750MB of each physical drive is consumed by overhead, leaving me with actual usable space of 3.25GB per drive.
CREATING THE STORAGE SPACE WITH PARITY
So, I created a single space, used Parity for the resiliency type. I set the size to 6GB, so that including the parity information, only 9GB would be consumed. Thus, I'm not using "thin provisioning", but instead ensuring that I have enough capacity to actually store my data.
A LOOK AT THE POOL AND SPACE WHEN DRIVE IS EMPTY
My confusion starts here. Even though I'm not yet storing a single file, approx 35% of my pool is being used. So, considering it's parity, and RAID (Raid 3 specifically from what I have read), I have to assume that it's just visually showing me that 1 out of my 3 drives will be used for parity, and thus nearly 33% will be consumed by parity.
COPY A SINGLE 1GB FILE TO MY NEW STORAGE SPACE
So, I copy in 1 single 1GB ISO file and place it into my Storage Space.
A look at my storage pool, leaves me confused. My pool usage went from 3.50GB used to 5.75GB used because of 1 single 1GB file????? If it wrote say 500MB to 1 drive, and 500MB to a 2nd drive, and consumed 500MB in parity on a 3rd drive...that would be 1.5GB....so I'm unsure how 2.25GB of space was reportedly used.
COPY A FEW MORE FILES TO THE STORAGE SPACE (Approx 4GB worth)
So, I copy some more files into my Storage Space. It's 7 files and totals 4GB of space
Here is the Properties of my Storage Space drive in Explorer;
Explorer looks right, approx 1.8GB free out of my 6GB volume (after copying in 4GB of files)
However, my Storage Pool is pretty much full. Huh? How can this be, I've only copied 4GB of files into a 6GB volume. How can it possibly be out of space??
Summary
3 x 4GB setup would provide 12GB of RAW space (say, if I did RAID 0)
With standard RAID 5 on a server, I would expect 2 x 4GB or so usable (around 8GB), with 4GB dedicated to parity
With Windows 8 Storage Spaces, I setup 6GB for what I thought would be "usable", leaving 3GB for parity and leaving around .75GB still free in the pool.
But yet, after copying 4GB of data, I'm maxed out. And trying to copy any more data to my Storage Space takes the Space "OFFLINE" as it's full.
So, it seems 4GB out of 12GB is usuable. So, it's 33% data, and 66% parity and overhead. How can this be this inefficient? A parity setup should provide more "usable" space than a 2-way mirror....which would give me 50%.
My Computer
System One
-
- OS
- Windows 7
- System Manufacturer/Model
- Self-Built in July 2009
- CPU
- Intel Q9550 2.83Ghz OC'd to 3.40Ghz
- Motherboard
- Gigabyte GA-EP45-UD3R rev. 1.1, F12 BIOS
- Memory
- 8GB G.Skill PI DDR2-800, 4-4-4-12 timings
- Graphics Card(s)
- EVGA 1280MB Nvidia GeForce GTX570
- Sound Card
- Realtek ALC899A 8 channel onboard audio
- Monitor(s) Displays
- 23" Acer x233H
- Screen Resolution
- 1920x1080
- Hard Drives
- Intel X25-M 80GB Gen 2 SSD
Western Digital 1TB Caviar Black, 32MB cache. WD1001FALS
- PSU
- Corsair 620HX modular
- Case
- Antec P182
- Cooling
- stock
- Keyboard
- ABS M1 Mechanical
- Mouse
- Logitech G9 Laser Mouse
- Internet Speed
- 15/2 cable modem
- Other Info
- Windows and Linux enthusiast. Logitech G35 Headset.