Advice please: Need to replace old Western Digital NAS HDD

[DeonH]

Hi and thanks for your advice. (I posted this on "Hardware" thread and didn't receive any replies. I probably should have posted it here.)

I have a Western Digital My Book Live Duo with 2 x WD 3TB NAS Red HDDs. One of the drives crashed.

Those HHDs are not available anymore. What am I to do now? I use my NAS as a backup for files I don't need to be in the cloud.
What will happen if I replace it with a 4TB drive? I can understand if the NAS will only be that of the smaller drive, but will it work? I have a RAID 1/stripe configuration where the two drives are mirrored?

I am on a budget for this and only want my NAS alive again.

Thanks very much.

 

[Snyper564]

the CHATGPT response

Hi and thanks for your advice. (I posted this on "Hardware" thread and didn't receive any replies. I probably should have posted it here.)

I have a Western Digital My Book Live Duo with 2 x WD 3TB NAS Red HDDs. One of the drives crashed.

Those HHDs are not available anymore. What am I to do now? I use my NAS as a backup for files I don't need to be in the cloud.
What will happen if I replace it with a 4TB drive? I can understand if the NAS will only be that of the smaller drive, but will it work? I have a RAID 1/stripe configuration where the two drives are mirrored?

I am on a budget for this and only want my NAS alive again.

Thanks very much.

Thanks — good details. Short version up front: yes, you can usually replace the failed drive with a larger drive (e.g. 4 TB) and the Duo will rebuild the RAID-1 mirror; after rebuild your usable volume will remain the size of the smaller member (so you’ll still see ~3 TB) unless you later replace the other drive and expand the partition. I’ll walk through the practical steps, recovery options if the Duo won’t rebuild, and a few warnings so you don’t lose data. Western Digital DocumentsWestern Digital

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What happens if you put a 4 TB drive in place of a failed 3 TB drive​

• RAID-1 mirrors block-for-block, so you can replace the dead drive with a same-or-larger drive and the enclosure will copy (rebuild) the good drive onto the new one. After rebuild the array will still present the size of the smallest drive (so it will still show ~3 TB until you also replace the remaining 3 TB drive and then grow the partition). Western Digital DocumentsWestern Digital

Practical, budget-friendly steps (do these in order)​

1. Identify which drive is dead — the My Book Live Duo’s front LED/WD utility or web UI will usually show which bay is failed. If unsure, power down and note which bay had errors. Western Digital Documents
2. Buy a replacement drive — a WD Red or similar NAS drive is recommended, but other brands/sizes will usually work. A larger drive (4 TB) is fine. If on a tight budget, you can buy a used 3 TB that matches the original to avoid extra work. (Community experience suggests matching family/model helps but isn’t strictly required.) Western DigitalReddit
3. Power down, swap the failed drive using the Duo’s drive access procedure (thumbscrews, pull tab) — the official manual describes the process. Then power on. Western Digital Documents
4. Let the Duo detect and rebuild — it should detect the new drive and start a rebuild to RAID-1 automatically or via the WD Drive Utilities / web UI. Monitor the RAID status in the web UI or WD software. Rebuilds can take many hours for multi-TB drives. Do not interrupt power while rebuilding. Western Digital Documents
5. After rebuild you’ll have a working RAID-1 mirror but still only the original usable capacity (≈3 TB). If you want the full 4 TB usable, you must replace the second drive too and then expand the data partition (this is a manual partition/resize step that tools like parted/resize2fs can do). Community posts explain how to do that. Western Digital

If the Duo won’t rebuild / enclosure problems​

• Some users report rebuild failures or enclosure firmware quirks (rebuild failing with some replacement drives, or firmware checking drive models/sizes). If that happens you have options: (a) try a different replacement (prefer WD Red similar model), (b) check logs via the web UI/SSH, or (c) remove the working drive and recover data on a Linux PC. There are community threads showing these exact failure modes and remediation attempts. SanDisk ForumsReddit

Quick guide to recovering files if the Duo refuses to rebuild​

If the Duo won't rebuild and you want to rescue files now (high priority if the surviving drive is healthy):

1. Power down the Duo and remove the working disk.
2. Attach that disk to a Linux PC (SATA or USB-SATA adapter).
3. On Linux run lsblk / sudo fdisk -l to find the drive and partitions. The data usually lives on a Linux partition (ext4 / an LVM inside).
4. Try mounting the data partition read-only, e.g.:
   

 

[DeonH]

Good afternoon and thanks very much for your reply.

This really helped a lot. I was afraid that I might not find a WD NAS drive in SA. I will look online for a 4TB WD RED for a start.

Thanks again and much appreciated.

 

[Jade @ Absolute Hosting]

As per @Snyper564's response you can replace a failed disk with a larger disk.

Those WD red drives are notorious for failing so I would suggest getting a WD Gold in its place if you want to stay with WD.