erasureDisks := er.getDisks()
	ridx := rand.Intn(len(erasureDisks))

	z.serverPools[0].erasureDisksMu.Lock()
	er.getDisks = func() []StorageAPI {
		erasureDisks[ridx] = newNaughtyDisk(erasureDisks[ridx], nil, errFaultyDisk)
		return erasureDisks
	}
	z.serverPools[0].erasureDisksMu.Unlock()

	uploadIDs = append(uploadIDs, res.UploadID)

	// Create multipart parts.