From mboxrd@z Thu Jan 1 00:00:00 1970 From: Adam Thompson Subject: Big-endian RAID5 recovery problem Date: Mon, 01 May 2017 16:39:07 -0500 Message-ID: <5c6e6e5d93d4056839e4f370e00a8e08@mail.athompso.net> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Return-path: Sender: linux-raid-owner@vger.kernel.org To: MUUG Roundtable , linux-raid@vger.kernel.org List-Id: linux-raid.ids So I've got 4 IDE HDDs, each with 3 RAID partitions on them, that were part of a RAID array in a now-very-dead NAS. Of course, I need to get data off them that wasn't backed up anywhere else. I've got a 4-port USB3 PCIe card, and 4 IDE/SATA USB adapters, and all the hardware seems to work. So far, so good. The problem is that the disks use the v0.90 metadata format, and they came from a big-endian system, not a little-endian system. MD superblocks *since* v0.90 are endian-agnostic, but back in v0.90, the superblock was byte-order specific. mdadm(8) on an Intel processor refuses to acknowledge the existence of the superblock. Testdisk detects it and correctly identifies it as a Big-endian v0.90 superblock. I'm reluctant to blindly do a forced --create on the four disks, because I'm not 100% certain of the RAID topology; there are at least two RAID devices, one of which was hidden from the user, so I have no a-priori knowledge of its RAID level or layout. The filesystems on the md(4) devices are, AFAIK, all XFS, and so should (hopefully) not have any endianness issues. I can't find any modern big-endian Linux systems... looks like all the ARM distros run in little-endian mode. Any suggestions on the best way to move forward? Thanks, -Adam