# US 2014/0208045 A1 · Managing metadata for logical volume managers

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- Number: US 2014/0208045 A1
- Document ID: US20140208045A1
- Status: Published application
- Kind: A1
- Application number: 13/747,162
- Filed: 2013-01-22
- Published: 2014-07-24
- Earliest claimed: 2013-01-22
- Assignees: Red Hat Israel, Ltd.
- Applicants: Red Hat Israel, Ltd.
- Inventors: Eduardo Warszawski; Ayal Baron
- Web page: https://patentgrep.com/patent/US20140208045A1

## CPC

- G06F 3/0665: {at area level, e.g. provisioning of virtual or logical volumes}
- G06F 3/0619: {in relation to data integrity, e.g. data losses, bit errors}
- G06F 3/067: {Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]}
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)

## Abstract

A logical volume manager (LVM) may manage a plurality of logical volumes and a plurality of drives in a logical data storage using metadata stored on the plurality of drives. The LVM may operate in one of two modes. In the first mode, the LVM may deleted uncommitted metadata on a drive and may use committed metadata on the drive when accessing a logical volume. In a second mode, the LVM may use committed metadata on the drive when accessing the logical volume and may refrain from deleting the uncommitted metadata.

## Claims

### Claim 1

A method comprising:
receiving a request to access a logical volume in a plurality of logical volumes;
determining, by a logical volume manager executable by a processing device, whether a committed metadata and an uncommitted metadata are in a drive used by the logical volume, wherein the logical volume manager is to manage the plurality of logical volumes and wherein the plurality of logical volumes use a plurality of drives;
determining whether to operate in a first mode or a second mode, when the committed metadata and the uncommitted metadata are on the drive;
removing the uncommitted metadata and using the committed metadata to access the logical volume, when operating in the first mode; and
using the committed metadata to access the logical volume and refraining from removing the uncommitted metadata, when operating in the second mode.

### Claim 2 (depends on 1)

The method of claim 1, wherein determining whether to operate in the first mode or the second mode comprises:
receiving a message indicating one of the first mode or the second mode; and
determining whether to operate in the first mode or the second mode based on the message.

### Claim 3 (depends on 1)

The method of claim 1, wherein determining whether to operate in the first mode or the second mode comprises:
accessing a flag stored in a memory; and
determining whether to operate in the first mode or the second mode based on the flag.

### Claim 4 (depends on 1)

The method of claim 1, further comprising:
when operating in the first mode:
receiving a message indicating the second mode; and
switching to the second mode.

### Claim 5 (depends on 1)

The method of claim 1, further comprising:
when operating in the second mode:
receiving a message indicating the first mode; and
switching to the first mode.

### Claim 6 (depends on 4)

The method of claim 4, further comprising:
receiving a second request to access the logical volume;
determining whether multiple committed metadata are in the drive; and
using a latest committed metadata to access the logical volume when there are multiple committed metadata in the drive.

### Claim 7 (depends on 4)

The method of claim 4, further comprising:
receiving a second request to modify the logical volume;
modifying the logical volume, based on the second request;
writing new metadata to the drive, wherein the new metadata is indicative of modifications to the logical volume; and
committing the new metadata.

### Claim 8 (depends on 1)

The method of claim 1, wherein the committed metadata indicates a mapping between the plurality of logical volumes and one or more of: the plurality of drives or portions of the plurality of drives.

### Claim 9

A system comprising:
a memory;
a processing device coupled to the memory; and
a logical volume manager, executable from the memory by the processing device, the logical volume manager to:
receive a request to access a logical volume in a plurality of logical volumes;
determine whether a committed metadata and an uncommitted metadata are in a drive used by the logical volume, wherein the logical volume manager is to manage the plurality of logical volumes and wherein the plurality of logical volumes use a plurality of drives;
determine whether to operate in a first mode or a second mode, when the committed metadata and the uncommitted metadata are on the drive;
remove the uncommitted metadata and use the committed metadata to access the logical volume, when operating in the first mode; and
use the committed metadata to access the logical volume and refrain from removing the uncommitted metadata, when operating in the second mode.

### Claim 10 (depends on 9)

The system of claim 9, wherein determining whether to operate in the first mode or the second mode comprises:
receiving a message indicating one of the first mode or the second mode; and
determining whether to operate in the first mode or the second mode based on the message.

### Claim 11 (depends on 9)

The system of claim 9, wherein determining whether to operate in the first mode or the second mode comprises:
accessing a flag stored in the memory; and
determining whether to operate in the first mode or the second mode based on the flag.

### Claim 12 (depends on 9)

The system of claim 9, wherein the logical volume manager is further to:
when operating in the first mode:
receive a message indicating the second mode; and
switch to the second mode.

### Claim 13 (depends on 9)

The system of claim 9, wherein the logical volume manager is further to:
when operating in the second mode:
receive a message indicating the first mode; and
switch to the first mode.

### Claim 14 (depends on 13)

The system of claim 13, wherein the logical volume manager is further to:
receive a second request to access the logical volume;
determine whether multiple committed metadata are in the drive; and
use a latest committed metadata to access the logical volume when there are multiple committed metadata in the drive.

### Claim 15 (depends on 13)

The system of claim 13, wherein the logical volume manager is further to:
receive a second request to modify the logical volume;
modify the logical volume, based on the second request;
write new metadata to the drive, wherein the new metadata is indicative of modifications to the logical volume; and
commit the new metadata.

### Claim 16

A non-transitory computer readable storage medium having instructions that, when executed by a processing device, cause the processing device to perform operations comprising:
receiving a request to access a logical volume in a plurality of logical volumes;
determining whether a committed metadata and an uncommitted metadata are in a drive used by the logical volume, wherein the processing device is to manage the plurality of logical volumes and wherein the plurality of logical volumes use a plurality of drives;
determining whether to operate in a first mode or a second mode, when the committed metadata and the uncommitted metadata are on the drive;
removing the uncommitted metadata and using the committed metadata to access the logical volume, when operating in the first mode; and
using the committed metadata to access the logical volume and refraining from removing the uncommitted metadata, when operating in the second mode.

### Claim 17 (depends on 16)

The non-transitory computer readable storage medium of claim 16, wherein determining whether to operate in the first mode or the second mode comprises:
receiving a message indicating one of the first mode or the second mode; and
determining whether to operate in the first mode or the second mode based on the message.

### Claim 18 (depends on 16)

The non-transitory computer readable storage medium of claim 16, wherein determining whether to operate in the first mode or the second mode comprises:
accessing a flag stored in a memory; and
determining whether to operate in the first mode or the second mode based on the flag.

### Claim 19 (depends on 16)

The non-transitory computer readable storage medium of claim 16, wherein the operations further comprise:
when operating in the first mode:
receiving a message indicating the second mode; and
switching to the second mode.

### Claim 20 (depends on 16)

The non-transitory computer readable storage medium of claim 16, wherein the operations further comprise:
when operating in the second mode:
receiving a message indicating the first mode;
switching to the first mode;
receiving a second request to modify the logical volume;
modifying the logical volume, based on the second request;
writing new metadata to the drive, wherein the new metadata is indicative of modifications to the logical volume; and
committing the new metadata.