Supported filesystems for USB drive

No ext4 support on the sparc NAS'. Your only options are going to be ext2/3, FAT32 or NTFS for external disks. ext2/3 is the best bet, FAT32 is nice but you've got character limits and no files over 4gb, NTFS is dog slow on the sparc NAS'.

x86 NAS units (NVX, Ultra, Pro) and the new ARM units (Duo v2 RND2000-200, NV+ v2 RND4000-200) have much improved NTFS performance. Unfortunately you can't simply migrate disks to one of these NAS units due to the different RAID format, so migration to one of these would involve transferring data across your network.

The Sparc NASes have slow CPUs and as USB backups are CPU intensive, performance for NTFS backups is terrible.

For USB disks, even on Sparc ReadyNAS the standard 4k block size is used. You can format the disk to use EXT3 via Volumes > USB Storage in Frontview. You will need to find EXT3 drivers for your PC.

FWIW I used GParted, booting one of my x86 PCs using Puppy Linux boot disk, to format my USB drive as EXT2. AFAICT the only diff between EXT2 and EXT3 is 3 is a journaling system, which I don't think you need (or want) for a USB drive that will be attached, backed-to, and detached again.

My backup USB drive started life as a 2TB NTFS, now a 2TB EXT2.

Dunno about your Duo, but I read here that EXT2 allows the fastest transfers of all the fs types, at least w/my NV+.

Thank you all for your answers.
I think I'm going to use ext3 formated by the NAS. And install ext3 FS driver on a few windows PC.

However I've got some bad sectors on the 1TB disk I want to plug on USB to the NAS.
I used a Linux PC to built the ext3 FS with R/W sector testing (it took quite a long time, but less than two days).
I understand the ext3 FS need to be built by the NAS, but I still want full R/W testing on sectors, to mark all bad sectors.
If I don't find the right option in the frontview I will do it with the command line.