Only seeing one of two HDDs

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napochan
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Only seeing one of two HDDs

Unread post by napochan » Fri Jul 13, 2018 8:04 pm

Hi, I just replaced a defective WD Red 2TB HDD with two (2) WD Red 4TB HDDs in a DS212j NAS. The intent is to run the 2 new drives in either a SHR or RAID1 configuration so I have data protection. I'm not sure of all the differences in these two options given both drives are the same size.

Anyway, the problem is after powering on and installing the latest DSM (6.2-23739 Update 1) I only see one of the drives (DISK2). All four status lights are green but only one of the drives shows any activity There is no visibility to the other drive in Storage Manager (or anywhere) and the one drive I can see is not visible on my network so I can't mount the drive in Win10.

I'm sure I missed a step somewhere but perhaps there's a problem with the second drive hardware )hoping that's not the case).

Appreciate any help to get on track.
...Tom
DS212j, 2 x 4TB WD Red, 6.2-23739 Update 1

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Rusty1281
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Re: Only seeing one of two HDDs

Unread post by Rusty1281 » Fri Jul 13, 2018 8:48 pm

It could be a problem with the drive or the sata connector for that drive. turn it off, open it and double check that you have connected everything correctly. If after that the disk is not visible, you will have to try with another one (or rotate the working one in its place).

If another drive works then you have your answer.
Synology DS918+ (4x4TB WD RED - RAID 5 with 2x250GB 960EVO NVMe) | Synology DS412+ (4x3TB WD RED - RAID 5) | RT1900AC

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napochan
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Re: Only seeing one of two HDDs

Unread post by napochan » Sun Jul 15, 2018 4:52 pm

Hi Rusty1281,
The drive connectors appeared to be seated well, but switching their positions did make a difference. Both drives are now recognized and the NAS is "Expanding (checking parity consistency ...)"; making progress but taking a LONG time to do so. When it completes, I'll try mapping the drive.

Given I have identical 4TB WD Red HDDs, is there any advantage to changing from SHR to RAID1 configuration?
...Tom
DS212j, 2 x 4TB WD Red, 6.2-23739 Update 1

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Re: Only seeing one of two HDDs

Unread post by Rusty1281 » Mon Jul 16, 2018 9:20 am

SHR vs conventional RAID it comes down to one thing. Do you plan to mix drives with different capacities or not? If you do then go with SHR if not then you can stick with RAID1.

SHR will have a need that the second drive you add later on will have to 4TB or larger in order to use more space. The point is that SHR has benefits in situations with multiple bays (more then 2) and if you do plan to mix HDD capacities.

Personally I use conventional raid setups considering all drives are the same and have no intention to mix then.
Synology DS918+ (4x4TB WD RED - RAID 5 with 2x250GB 960EVO NVMe) | Synology DS412+ (4x3TB WD RED - RAID 5) | RT1900AC

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Re: Only seeing one of two HDDs

Unread post by drabisan » Mon Jul 16, 2018 4:45 pm

Rusty1281 wrote:
Mon Jul 16, 2018 9:20 am
Personally I use conventional raid setups considering all drives are the same and have no intention to mix then.
I followed the same logic. But 4 years down the road I had to move from 4 to 8 bays and not setting up a SHR at first was a time consuming decision.
Buying some more 3T drives 4 years later it would be a bad economic decision so I bought larger drives and a RAID5 was not an option.

Although following a standard RAID do sound like the best idea instead of pursuing a proprietary path, after a certain amount of data, migration can become a PITA and suddenly a proprietary SHR sounds so much better.

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Re: Only seeing one of two HDDs

Unread post by telos » Mon Jul 16, 2018 7:34 pm

You can't go wrong w/SHR. I don't see any good reason to stay exclusively w/RAID.

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Re: Only seeing one of two HDDs

Unread post by Rusty1281 » Mon Jul 16, 2018 9:50 pm

drabisan wrote:
Mon Jul 16, 2018 4:45 pm
I followed the same logic. But 4 years down the road I had to move from 4 to 8 bays and not setting up a SHR at first was a time consuming decision.
Buying some more 3T drives 4 years later it would be a bad economic decision so I bought larger drives and a RAID5 was not an option.

Although following a standard RAID do sound like the best idea instead of pursuing a proprietary path, after a certain amount of data, migration can become a PITA and suddenly a proprietary SHR sounds so much better.
You are right on that front for sure. Considering I always got a new unit with fresh drives I never planed to migrate old disk to new units. But in that case SHR would be a much elegant solution.
Synology DS918+ (4x4TB WD RED - RAID 5 with 2x250GB 960EVO NVMe) | Synology DS412+ (4x3TB WD RED - RAID 5) | RT1900AC

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