Synology Hyper Backup to external USB drive: Exception occurred while backing up data (Disk I/O error)

I am attempting to backup my entire Synology¹ DS415+ NAS volume to an external Western Digital My Book 8 TB USB drive, using Hyper Backup.

The backup worked fine for about 10 hours, but suddenly failed at around 80 % completion. In the Hyper Backup log, I see:

[Local][Name_of_backup_job] Exception occurred while backing up data. (Disk I/O error.) [User: admin, Path: /volumeUSB1/ushbshare1-2/[backup_file.hbk/Pool/0/26/604.bucket]

The format of the external drive is HFS+, formatted on a Mac as "Journaled". The drive usage is about 2.5 / 8 TB after the incomplete backup. Before backing up, the drive passed the macOS Disk Utility Diagnostics test. I haven't run Western Digital's own diagnosis tool yet. The drive is just a few months old and I haven't had it plugged in except when backing up, but I guess that doesn't matter much when dealing with these things.

I've previously been able to backup to the external USB drive while it was formatted in exFAT, but the other day I reformatted it to HFS+ because of mounting problems in macOS, as outlined in this thread. Before reformatting, I was able to successfully complete a Hyper Backup integrity test.

The NAS volume itself is in SHR-2 and the backup job is for Data Backup (not LUN).

Is there a way to get better details of this I/O error? What does it mean, and what should be my next steps?

_{¹NB: I have asked on the Synology forums for help.}

Winterflags

Posted 2017-08-21T21:31:38.810

Reputation: 958

Answers

I have this Disk I/O error issue too:

[Local][Backup-NAS-Seagate2T] Exception occurred while backing up data. (Disk I/O error.) [User: admin, Path: /volumeUSB1/usbshare/nas_1.hbk/Pool/chunk_index/232.idx]

it's a fairly new 2T external USB drive.

Jan

Posted 2017-08-21T21:31:38.810

Reputation: 11

1I got this response from Synology, don't know what to make of it: Sadly, I/O errors are generally not reported by manufacturer's test tools as these are generally looking for sector error and the like. Writing a large amount of data to the drive seems to be causing an I/O error which is then failing the backup. If this is a continuous issue, what I would suggest is creating multiple smaller tasks that provide the same function as one larger task, this way, you will eventually end up with a full backup of your data on the external drive, rather than a single task that will continually fail. – Winterflags – 2017-09-20T07:40:01.157

Also in the support response: I can confirm from the message you are seeing that the I/O error that it is reporting is indeed on the external drive and not on the internal drives of the NAS. This could be caused by a various number of things, the USB ports, the cable, the enclosure, and so on, it might not even be that the drive itself is failing. – Winterflags – 2017-09-20T10:04:12.570

I know this question is like 3 years old, but for anyone who finds this on google, try formatting as EXT4 instead of NTFS.

realmature

Posted 2017-08-21T21:31:38.810

Reputation: 1