Data is striped across every member with no parity and no mirror, so a lost disk takes a proportional slice out of every file on the volume. Be careful with anyone offering to rebuild one from parity — there is none.
Nothing is held in reserve on a stripe, so recovery means reading every member including the failed one and reassembling from images. How much returns is decided by how much of the casualty can be read.
Every other RAID level keeps something back. RAID 1 keeps a whole second copy. RAID 5 keeps parity that can reconstruct any single missing member. RAID 0 keeps nothing at all — it splits data across every disk purely for speed, and each disk holds a fraction of every file on the volume.
So when one member of a stripe fails, you have not lost that disk's share of the files. You have lost a slice out of every single file. A document spread across four disks with one missing is missing a quarter of itself, distributed evenly through its length.
This is why anyone offering to rebuild a RAID 0 from parity should be treated with suspicion. There is no parity. The only route to the data is recovering the failed disk itself as a physical device.
The failed disk is recoverable. Then so is the array. The disk is imaged like any single drive, the stripe parameters are derived, and the volume is reassembled from the images of all members.
The failed disk is partially recoverable. You get a proportional result. Where 90% of the failed member reads, roughly 90% of the volume reassembles — but damage is spread across every file rather than concentrated in some.
The failed disk is unrecoverable. Then large files are gone and small ones may survive. A file entirely contained within one stripe unit on a surviving disk can still be carved out. Anything larger cannot be completed.
Someone has already rebuilt over it. The worst case. Initialising or recreating a RAID 0 writes new metadata and frequently new stripe geometry, and there is no redundancy to absorb that.
Power the array down and leave it down. A degraded stripe serves nothing useful and every additional hour risks a second member developing problems.
Label every disk with the position it occupied. Bay order is part of the stripe geometry, and while it can be derived mathematically, having it recorded saves real time.
Send every member, including the failed one. Especially the failed one — it is the whole job. An array sent without its dead disk cannot be reassembled, because there is nothing to reconstruct the missing slices from.
Where the controller is gone or its configuration was never recorded, the stripe has to be worked out from the member disks themselves. Disk order, stripe unit size, start offset and whether the controller used a left or right arrangement all have to be established.
The method is to look for structures that only make sense when the parameters are correct. A file system superblock appears at a predictable place; a large file's internal structure runs continuously. Test a candidate geometry, and either those structures line up or they do not. Wrong parameters produce output that looks almost plausible, which is why verification against known file structures matters more than getting a result at all.
Once the geometry is confirmed, the volume is reassembled from images rather than from the disks themselves, so nothing further is risked.
Only by recovering that physical disk. There is no parity and no mirror, so nothing can compute the missing data. If the failed member is recoverable, the array is.
Roughly in proportion, but spread across everything. A 90% read on the failed member does not give you 90% of your files intact — it gives you most files with small gaps distributed through them.
Because every file is split across all four. Losing one member removes a quarter of every file rather than a quarter of your files. That is what striping means.
Yes, including the failed one, and labelled by position if possible. Missing members cannot be reconstructed on RAID 0 because there is nothing held in reserve to reconstruct from.
For scratch space and rendering caches where speed matters and loss is acceptable, yes. For anything you would be upset to lose, no — it multiplies your failure risk by the number of disks.
From £500 +VAT for array work, fixed in writing after the free 48-hour diagnostic. Where the failed member also needs clean-air work, that is identified and quoted at the same point.