CONTROL METHOD AND STORAGE DEVICE

• US 20090313498A1
• Filed: 06/09/2009
• Published: 12/17/2009
• Est. Priority Date: 06/13/2008
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: TAKAHASHI, Hideo, IGASHIRA, Atsushi, KUBOTA, Norihide, KONTA, Yoshihito
• Granted Patent: US 8,225,136 B2
• Time in Patent Office: Days
• US Class Current: 714/6
• CPC Class Codes: G06F 11/1076 Parity data used in redundant arrays of independent storages, e.g. in RAID systems
• CPC Class Codes: G06F 2211/1059 Parity-single bit-RAID5, i.e. RAID 5 implementations

Abstract

A control method includes the steps of storing data in a cache; generating parity data corresponding to the data stored in the cache and storing the parity data in a buffer; writing the data stored in the cache and the parity data stored in the buffer into a plurality of the storage units; reading the data and the parity data from the plurality of storage units; checking error over the read out data by using the read out parity data; storing, if an error is detected in the read out data and the read out parity data, data for reading a plurality of data constituting a stripe in each of the plurality of storage units in the buffer, regenerating parity data by using the plurality of data readout from the storage units; and overwriting the plurality of data and the parity data into the plurality of the storage units.

Claims

1. A control method for controlling a controller connected to a plurality of storage units storing data, the controller including a cache and a buffer, the method comprising:

storing data in the cache;

generating parity data corresponding to the data stored in the cache and storing the parity data in the buffer;

writing the data stored in the cache and the parity data stored in the buffer into the plurality of the storage units;

reading the data and the parity data from the plurality of storage units;

checking error over the read out data by using the read out parity data;

storing, if an error is detected in the read out data and the read out parity data, data for reading a plurality of data constituting a stripe in each of the plurality of storage units in the buffer,

regenerating parity data by using the plurality of data readout from the storage units; and

overwriting the plurality of data and the parity data into the plurality of the storage units.

2. The control method according to claim 1, wherein the reading step reads the data and the parity data which constitutes a stripe in the plurality of storage units with the read out data.

3. The control method according to claim 1, the control method further comprising:

when an error is detected in the read out data and the read out parity data, generating a reading information indicative of reading out data other than the error detected parity data so as to regenerating the parity data.

4. An apparatus comprising:

a plurality of storage units for storing data;

a cache for storing data;

a buffer for storing parity data corresponding to the data; and

a controller for writing the data and the parity data into the plurality of the storage units in accordance with a process comprising;

generating parity data corresponding to the data stored in the cache and storing the parity data in the buffer;

writing the data stored in the cache and the parity data stored in the buffer into the plurality of the storage units;

reading the data and the parity data from the plurality of storage units;

checking error over the read out data by using the read out parity data;

storing, if an error is detected in the read out data and the read out parity data, data for reading a plurality of data constituting a stripe in each of the plurality of storage units in the buffer,

regenerating parity data by using the plurality of data readout from the storage units; and

overwriting the plurality of data and the parity data into the plurality of the storage units.