Dell DX6000G Release Notes

Brand: Dell

Model: DX6000G

Type: Release Notes

The Dell DX6000G is an enterprise-class storage platform designed to meet the demanding needs of today's data-intensive applications. With its powerful hardware architecture, flexible software features, and comprehensive data protection capabilities, the DX6000G is an ideal solution for a wide range of storage requirements, including large-scale virtualization, high-performance computing, and mission-critical applications.

DX Storage CFS Release Notes

Version 2.6.1

DX Storage CFS Release Notes: Version 2.6.1

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Version 2.6.1

March 2011

Table of Contents

1. Version 2.6.1 ....................................................................................................................... 1

1.1. Introduction ............................................................................................................... 1

1.2. Changes in Release 2.6.1 ......................................................................................... 1

1.3. Previous Changes in Release 2.6 .............................................................................. 1

1.4. Previous Changes in Release 2.5 .............................................................................. 1

1.5. Limitations of this Release ......................................................................................... 2

1.6. Upgrading CFS ......................................................................................................... 3

1.6.1. Upgrading from Versions 1.x ........................................................................... 3

1.6.2. Upgrading from Version 2.0 ............................................................................ 3

1.6.3. Upgrading from Version 2.5 ............................................................................ 3

1.7. Application and Configuration Notes ........................................................................... 3

Version 2.6.1

March 2011

Chapter 1. Version 2.6.1

1.1. Introduction

DX Storage Cluster File Server (CFS) is a native DX Storage application that presents a DX Storage

storage cluster as a standard Linux file system, enabling software that uses a file system to store

into DX Storage. These release notes contain late-breaking information about DX Storage Cluster

File Server 2.6.

1.2. Changes in Release 2.6.1

This release enhances and extends the previous major release of DX Storage Cluster File Server in

the following ways:

• An issue that could cause CFS to become unresponsive under stress conditions has been

resolved.

1.3. Previous Changes in Release 2.6

This release enhanced and extended the previous major release of DX Storage Cluster File Server

in the following ways:

• Memory management has been optimized to be more efficient.

• CFS now supports migration of a 1.2.x MySQL database to CNS. Please contact your support

resource for migration instructions.

• CNS now imposes max limits for items (both files/sub-folders) per folder (default 100K), file

attributes per file (default 50K) and links per file (default 10K). These limits make the software

more resilient in extreme use cases like when connectivity to DX Storage is lost for an extended

period of time. If the limits are exceeded the addition of new attributes, links or folder items will be

prevented and the CNS log will show errors that include the phrase CNS_TOOMANY.

• A timeout on an open SCSP connection to a DX Storage node has been added with a default of

10 seconds to prevent namespace hangs if the DX Storage should not respond for any reason

within the timeout window.

1.4. Previous Changes in Release 2.5

This release enhanced and extended the previous major release of DX Storage Cluster File Server

in the following ways:

• The timescape feature supported in previous versions of CFS is now supported in version 2.5.

Timescapes provide continuous snapshot functionality, allowing an administrator to mount a

historic, read-only view of a file system at any past time and view and/or copy previous versions of

files.

• CFS now runs on Red Hat Enterprise Linux 6.0. CFS is not compatible with older versions of

RHEL as they do not contain the required kernel and library versions.

The previous Ubuntu-based packaging is no longer available with version 2.5 and all future

versions but will continue to be supported with version 2.0 for the duration of your support terms.

• Several command-line support tools have been added to allow reporting and management of CFS

configuration and data. Please reference the 'Support and Management Utilities' section of the

Setup and Configuration Guide for complete details.

Version 2.6.1

March 2011

• The CNS garbage collection process has been enhanced to prioritize garbage collection for large

XML containers with a high percentage of historical data for faster memory reclamation.

1.5. Limitations of this Release

These are the known issues and operational limitations that exist in this release of CFS 2.5:

• Membership in a Large Number of ACL Groups Users with memberships in a large number of

ACLs groups (>31) may experience permission issues when accessing directories.

• Zeroconf Node Discovery If using Zeroconf for discovering the list of DX Storage nodes and

using a cluster name with periods in it, the periods must be replaced with underscores to ensure

proper node discovery.

• Red Hat 'hugepages' Compatibility The recently added Red Hat 'hugepages' feature has

been found to be incompatible with CFS and other applications, often resulting in kernel hangs

particularly under high stress scenarios. As a result it is highly recommended that huge pages

be disabled. Please reference the 'Installation' chapter of the Setup and Configuration Guide for

complete details.

• NFS v4 Compatibility Files written to CFS via NFS version 4 may not get all their permissions

properly set, and NFS v4 is therefore not supported. NFS version 3 is supported.

• Firewall Rules for mDNS RHEL 6 firewall blocks mDNS lookups by default. In order to use the

Zeroconf configuration to find DX Storage nodes, customers must enable mDNS in the firewall.

Steps:

1. From a root command shell run: system-config-firewall-tui

2. The "Firewall: [*]" checkbox should be checked with the spacebar to enable it.

3. Tab to the "Customize" button, cursor down to "Multicast DNS (mDNS)" and use the

spacebar to enable it.

4. Click Tab or OK on the remaining screens and then "Yes" on the final Warning screen .

• Passwords when using DX Storage 4.x and CFS Installations running DX Storage 4.x should

use clear text administrative passwords, not hashed ones, to ensure CFS is able to write

all journals and CNS containers using replicate on write for maximum data protection. After

upgrading to DX Storage 5.0 use of hashed passwords can be resumed.

• Name Space Restarts Restarts of the Cluster Name Space may become increasingly longer as

the number of objects in the name space grows over time.

• SELinux Mount Interference on Reboot SELinux may prevent files shares from mounting

after a reboot. To disable SELinux on a test environment, edit the /etc/selinux/config file and set

'SELINUX=disabled'.

• NFS Stale File Handle Errors Users may occasionally receive 'Stale NFS file handle' errors in an

NFS client when writing or reading to CFS. To ensure all data is transmitted correctly, files should

be closed and reopened when one of these errors is encountered.

• DF Inode Reporting CFS does not report inode information in response to a 'df -i' command to

the filesystem. Applications needing to determine available space should query based on blocks

rather than inodes.

Version 2.6.1

March 2011

• Large NFS Writes with Slow Disks Due to the way NFS closes files, users writing large files

over NFS with slow disks in their CFS server may see multiple revisions of each file saved to DX

Storage instead of a single large file.

• Log Errors on Mac Clients Running Microsoft Powerpoint When opening and saving Mac

Microsoft Powerpoint files on a CIFS exported share, users may occasionally see warnings in the

log. These errors do not impact file data and are not visible from the actual application.

• Deleting While Writing over Samba When using a Samba mounted share, a delete issued for

a file that is being actively written may result in undeleteable hidden files that prevent a directory

from being deleted. Restarting Samba will eliminate these files and allow the directory to be

removed.

• File Sync Option In order to maximize performance with the CFS revisioning file system, files

written with the O_SYNC flag to the CFS file system are not synchronized to the spool directory

prior to reporting a success return code. Synchronizing each block can cause performance

degradation without guaranteeing greater reliability.

• ACLs Exceptions While default access ACLs can be set for a directory with CFS, child objects

do not always correctly inherit the default. Default ACLs are therefore not recommended for use

with CFS. Also, users with read-only ACLs permissions will also have execute permissions and

ACLs with masks are not supported.

• Creating Read-only Files Applications that utilize the open function with the O_CREAT and

O_RDONLY flags to create new, read-only files are not recommended for use with CFS 2.0 or

later, as this may cause these empty files to not be persisted to DX Storage until reopened.

1.6. Upgrading CFS

1.6.1. Upgrading from Versions 1.x

The 2.6 release now supports data migration from the previous 1.x versions of CFS that utilized a

MySQL database. Please contact your support resource for migration instructions.

1.6.2. Upgrading from Version 2.0

2.0 Ubuntu-based installations can migrate to 2.6 by installing a new Red Hat server with

configuration data and shares that exactly mirror the current installation and then switching out the

newly created CNS rootID with the previous Ubuntu-based one. The same DX Storage cluster must

be used for both the old and the new installation. Please reference the 'Restoring CFS' section of

the Setup and Configuration Guide for complete details.

1.6.3. Upgrading from Version 2.5

2.5 Red Hat-based installations can upgrade to 2.6 by stopping all services, installing the new

version and restarting. Please reference the Upgrading CFS section of the Setup and Configuration

Guide for complete details.

1.7. Application and Configuration Notes

Special attention should be paid to the following items when using CFS:

• CNS Memory Utilization The Cluster Name Space (CNS) will use up to 2GB of RAM by default

and then gradually start to reclaim memory to keep the process close to 2GB of usage. The 2GB

soft limit can be modified if necessary. Please contact your support representative for modification

instructions.

Version 2.6.1

March 2011

• Maximum Network Connections CFS will support a maximum of 10000 open network

connections at any one time.

• Maximum File Name Length The maximum supported length for the name of a file in CFS is 255

characters. Attempting to create a filename that exceeds this length will result in an error that the

filename is too long.

• Temp Space Configuration A large spool space (> 200GB) is not necessary, and indeed can

hurt performance in some scenarios. The spool directory's file system should be configured with

enough space to keep a maximum of 100,000 files.

• Space Reporting When reporting file system capacity via a tool like 'df', CFS will under-report DX

Storage available capacity by 10% as a reserve for files currently in the spooling state.

• Dependent Service Restart after CFS Process Error The monitoring service that restarts DX

Storage CFS in the event of an error cannot restart other dependent services like NFS or Samba

as they may be in use by other applications. A restart of those services may be required to restore

full access to CFS.

• Conflicting Reads and Truncates Truncating a large file while it is being read can possibly result

in the last section of the read file containing null bytes to fill in the portion that was truncated.

• Samba Case Sensitivity By default Samba is case insensitive which can have a significant

impact on performance, particularly when storing a large number of files in a single directory.

Tuning the Samba parameters to support case sensitivity may provide performance

improvements but is not appropriate for all use cases. Please contact your technical account

manager for more information on the tradeoffs between performance and case sensitivity.

Dell DX6000G Release Notes

Dell DX6000G Release Notes

Dell DX6000G Release Notes

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