def update_data_block(virtual_block_number, block_data):
server_number, block_number = block_number_translate(virtual_block_number)
client_stub.update_data_block(block_number, block_data, server_number)
for j in range(num_servers
): #finding the server number on which parity is located
if mapping[block_number][j] == 'P':
xor(j, block_data, block_number)
def free_data_block(vir_block_number):
if vir_block_number != -1:
server_number, block_number = block_number_translate(vir_block_number)
global mapping
mapping[block_number - initial_blk_number][server_number] = 0
#print(mapping)
block_data, state = client_stub.get_data_block(block_number,
server_number)
for j in range(
num_servers
): #finding the server number on which parity is located
if mapping[block_number][j] == 'P':
# xor(j,block_data,block_number)
old_data, state = client_stub.get_data_block(block_number, j)
a = old_data
b = block_data
data = ''.join(chr(ord(a) ^ ord(b)) for a, b in zip(a, b))
client_stub.update_data_block(block_number, data, j)
client_stub.free_data_block(server_number, block_number)
def xor(server_number, new_data, block_number):
print "Writing to Parity Block"
old_data, state = client_stub.get_data_block(
block_number, server_number) #getting old parity
if state is False: #when the parity resides on a server that is corrupted, then XOR data from all the other servers and get the parity
for servers in range(num_servers):
if servers != server_number:
a = old_data
b = new_data
b, state = client_stub.get_data_block(block_number, servers)
b = ''.join(b)
parity_data = ''.join(
chr(ord(a) ^ ord(b)) for a, b in zip(a, b))
a = parity_data
else:
a = old_data
b = new_data
data = ''.join(
chr(ord(a) ^ ord(b))
for a, b in zip(a, b)) #XORing the old parity with new data
check_parity(block_number, server_number)
client_stub.update_data_block(
block_number, data, server_number
) #writing the new parity (while writing the data block)
def update_data_block(block_number, block_data):
client_stub.update_data_block(block_number, block_data)
def update_data_block(block_number, block_data):
if (RAID_5.has_been_called == True):
client_stub.update_data_block(block_number, block_data)
if (RAID_1.has_been_called == True):
client_stub_RAID1.update_data_block(block_number, block_data)
def update_data_block(block_number, block_data, delay_sec):
client_stub.update_data_block(block_number, block_data, delay_sec)