Synology ext4 volume - Issues reading on other computers?

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Data
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Synology ext4 volume - Issues reading on other computers?

Postby Data » Fri Feb 17, 2017 1:14 am

Hey everyone, I have an interesting puzzle on my hands. :?

I have a DS216J which I am attempting to back up to an 8TB drive (WD Red) in a USB 3 enclosure, but am having issues with the USB drive's filesystem on other computers.

In particular, if I partition and format the USB drive as a single 8TB ext4 volume on my Mac (using Paragon extFS), the drive shows up as two partitions when plugged into the Synology - one very small partition, and one medium size partition, much smaller than the 8TB drive capacity. I instead re-formatted the drive on the DS216J, and was then given a single 8TB filesystem which the Diskstation gave a clean bill of health. I copied approximately 6TB of data to the drive.

However, upon bringing it back to my Mac to verify the backup, Paragon ExtFS finds errors with the volume, and will only mount it as read-only. The volume verification (e2fsck 1.42.13) says that the filesystem size (according to the superblock) and the physical size of the device differ, and says either the superblock or the partition table is likely to be corrupt. It also does an inode check, which produces an exceptionally long list of warnings that "inode xxx has INDEX_FL flag set on filesystem without htree support". The files *appear* to all be there when viewed on the Mac, and the DiskStation finds no faults when the drive is plugged back into it.


Is there a configuration to the ext4 file system that I might be missing that is hurting compatibility? Or are there known issues or incompatibilities with ext4 support on the Synology? I'm running DSM version "6.0.2-8451 Update 9". Given its age and widespread usage, I would have thought ext4 support would be pretty stable on both sides. I should also add that this external drive is brand new, has no SMART warnings, and passed a full week of 'badblocks' stress testing before being put into use here for the backups.


Any help would be greatly appreciated! Thanks.
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Re: Synology ext4 volume - Issues reading on other computers?

Postby sincarne » Fri Feb 17, 2017 7:45 pm

Format to EXT4 on the synology instead of a Mac as Macs dont do ext4 natively so this app you mention could be bad
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Re: Synology ext4 volume - Issues reading on other computers?

Postby Data » Fri Feb 17, 2017 7:58 pm

sincarne wrote:Format to EXT4 on the synology instead of a Mac as Macs dont do ext4 natively so this app you mention could be bad


Thanks for the reply. As I mentioned, I did end up formatting the drive as ext4 from the Synology itself... but that is the format that gave the errors on the Mac. Last night I tried another test, and connected this Synology-formatted USB drive to a Linux machine, and fsck on that machine (e2fsck 1.43.3) gave the same errors as the fsck under Paragon ExtFS on the Mac. :( So a standard Linux install ALSO thinks there are problems with the ext4 volume.

I hate to go backwards, but part of me is tempted to just re-format the drive to ext3 and see if that works any better. :?
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Re: Synology ext4 volume - Issues reading on other computers?

Postby sincarne » Fri Feb 17, 2017 8:02 pm

Data wrote:
sincarne wrote:Format to EXT4 on the synology instead of a Mac as Macs dont do ext4 natively so this app you mention could be bad


Thanks for the reply. As I mentioned, I did end up formatting the drive as ext4 from the Synology itself... but that is the format that gave the errors on the Mac. Last night I tried another test, and connected this Synology-formatted USB drive to a Linux machine, and fsck on that machine (e2fsck 1.43.3) gave the same errors as the fsck under Paragon ExtFS on the Mac. :( So a standard Linux install ALSO thinks there are problems with the ext4 volume.

I hate to go backwards, but part of me is tempted to just re-format the drive to ext3 and see if that works any better. :?


sorry did not see. maybe exfat?
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Re: Synology ext4 volume - Issues reading on other computers?

Postby Data » Sat Feb 18, 2017 3:37 am

sincarne wrote:sorry did not see. maybe exfat?

I could do exFAT I suppose... but I actually don't have any Windows machines, and the patent encumbrance means that exFAT has an additional module to purchase on the Synology and a bit less support under Linux. :| So I probably would only go that way as a last resort.... Thanks though!

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