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The Graveyard - Products No Longer Supported => D-Link Storage => DNS-321 => Topic started by: tqn on March 15, 2009, 08:34:22 PM

Title: Quick RAID 1 Question
Post by: tqn on March 15, 2009, 08:34:22 PM

My DNS-321 has 2 WD 640GB disks running in RAID 1. In the STATUS page, the Hard Drive Info section shows the following:

---------------------------------------------------
Total Drive(s):                 2

Volume Name:                 Volume_1
Volume Type:                   RAID 1
Sync Time Remaining:         Degraded
Total Hard Drive Capacity:  627775 MB
Used Space:                     521562 MB
Unused Space:                 106213 MB

Volume Name:                  Volume_2
Volume Type:                    JBOD
Total Hard Drive Capacity:   2477 MB
Used Space:                       24 KB
Unused Space:                   2477 MB
---------------------------------------------------

Shouldn't the "Volume Type" for disk 2 be "RAID 1" (instead of "JBOD") as well? Also the Search Utility shows 2 volumes that can be connected separately. Did I set it up wrong at the beginning? Yeah, I need to re-sync the drives (again). Thanks.

--tn
Title: Re: Quick RAID 1 Question
Post by: D-Link Multimedia on March 15, 2009, 09:00:04 PM
No, your initial setup of Raid1 must have been less than 100% of your disks. If you specified anything under the 640GB raid 1 the remaining space is turned into a Jbod.
Title: Re: Quick RAID 1 Question
Post by: tqn on March 16, 2009, 02:24:51 AM

Thanks for the explanation. The 2 disks are exactly of the same model, and I am pretty sure I specified the whole disk. Oh well, I'll re-format again.
Title: Re: Quick RAID 1 Question
Post by: fordem on March 16, 2009, 05:23:21 AM
You're looking at a relatively small Volume_2 there - it's not unusual for two drives of the same "nominal" capacity (even the same make & model) to have different capacities (although this is usually just a few megabytes, rather than the 2+ GB shown here)

If this were to happen, it is theoretically possible for the 321 to create the drive configuration shown here, even after the maximum available space was used for a RAID1 volume.

There is a "flip side" to this worth mentioning (and this is how I actually discovered this), if you had a failed drive and replaced it with one with just a few megabytes less capacity, the system would be unable to rebuild the array - this happened to me several years ago with a RAID1 pair in an IBM server, and was the cause of considerable head scratching as I was using supposedly identical drives - make, model & capacity - turned out that the replacement had 2MB less space than the one that had failed.

By the way - you should be able to see this at the format screen - when you enter the desired capacity, the unit should display any remaining space, before you click that final Next or Apply button.
Title: Re: Quick RAID 1 Question
Post by: tqn on March 16, 2009, 06:52:23 PM

Thanks for sharing your experience! I would never expect there's a capacity difference from the two same model and make drives. I'll leave my DNS-321 alone.