Einarc is a solution for all this hassle: it's a universal storage RAID command line interface and an API that provides management for various hardware/software RAID devices. Einarc would autodetect hardware RAID on a server, would automatically downloaded required command-line tool and wrap it around in a convenient and easy to learn syntax. It works as a translator that makes it possible for an admin to control all these devices using simple terms like "physical disc", "logical disc", "adapter", etc., while transparently converting these requests to proprietary RAID paradigms.

For example, no matter what hardware RAID is used on a server, it's always easy to check state of its logical discs with Einarc. Just issue a "logical list" command and grep for "degraded" discs to see if there's a failure. Same thing goes for any event log reading/monitoring (log list), RAID array creation or modification (logical add), setting up various adapter options, etc.

Version 1.3 of Einarc came after massive half a year of work on it and sports the following features:

• Support for 3ware / AMCC controllers.
• Full read/write support of Linux software RAIDs.
• Updated all proprietary utilities URLs, pumped up version numbers, fixed wrapper regular expressions to support new versions of CLIs.
• Added new calculated fields in adapter_info: PCI product/subproduct and vendor/subvendor IDs. These allow precise identification of PCI devices related to adapters shown by Einarc.
• Fuller BBU support for Adaptec adapters.
• Multiple stability and build fixes.

As of version 1.3, the following RAIDs are supported:

• Adaptec SCSI and SAS/SATA
• AMCC/3ware
• Areca
• LSI MegaRAID SCSI/SAS/SATA
• Fusion/MPT HBA
• Linux software MD device (for sake of completeness)

Einarc v1.3 is a part of Inquisitor, a free Linux hardware stress testing and benchmarking platform, which uses Einarc extensively for HDD testing purposes.

Solid state drives (SSD) have many advantages over traditional spinning-platter hard drives including no noise, low power and heat generation, good resistance to shock, and most importantly, extremely low seek times. To see just how much an SSD might improve performance, I used Bonnie++ to benchmark a contemporary SSD as it might be used in a laptop computer.

This article assumes you are using GRUB as your bootloader, and that you have an existing, working, and bootable installation of Linux. This document (should) contain every command required to convert a single drive over to a fully mirrored RAID-1 system. During the process, you will have an opportunity to change the filesystem type (perhaps from Ext2 to XFS or ReiserFS); I will be migrating partitions from Ext2 to Ext3 and XFS.

In general, it’s fairly easy to recognize a Nested RAID configuration because it will have two or more numbers designating the combination of standard RAID levels. For example RAID-10 uses both RAID-1 and RAID-0 to create the Nested RAID configuration. RAID-51 uses RAID-5 and RAID-1 to create that Nested RAID configuration, and so on.

The order of the numbers in the Nested RAID designation is important. The first number to the left is the lowest standard RAID level used (just above the disks). The next highest RAID level is the next number to the right and so on.

What self-respecting geek doesn't get the warm fuzzies at the mere mention of the RAID. With the rising GB to Dollar ratio, we felt it was a good time to feature a project that takes Pure Geekieness(TM) and mixes in a good helping of do it your self. Where else are you going to store all those MP3s (legally obtained, of course)? On a single 200 GB Drive? Or a RAID 5 Array? Take you pick, I know where I will be storing mine.

Sun says ZFS and the new data replication model it includes, RAID-Z, can eliminate the need for additional expensive hardware. RAID-Z is a new take on the RAID systems that many system administrators employ promote data integrity. Sun believes the ZFS filesystem with RAID-Z offers "virtually unlimited capacity, provable data integrity, and near-zero administration."

ZFS provides transactional semantics -- which stores data changes and updates at once, rather than writing to disk as a file is altered -- and end-to-end data integrity, according to Sun developer Jeff Bonwick.

Our team at LinuxForce recently put together a Debian server with LVM on a software RAID5 volume. This has been possible through complex installation procedures in the past, but today the Debian Etch installer is capable of handling such an installation if you follow the proper steps, which I outline in this article.

Among other things, we needed the flexibility to write partition tables for Xen on the fly, dependability that would allow a generous replacement window when harddrives failed, and as little possibility of data loss and downtime through harddrive failure as possible.

Software RAID is an emulation of what hardware RAID devices do. There are some disadvantages of software RAID compared to hardware RAID: some disk device write performance is lost; there is additional processing burden on the server; and the hot-swappability of disk units is not available. However, the cost of standard disk controllers and devices is much less than those that support RAID modes in hardware. Often a combination of hardware RAID devices and software RAID will provide a flexible and maintainable solution that fits within the availability and budget constraints of the application.

In this example I have two hard drives, /dev/sda and /dev/sdb, with the partitions /dev/sda1 and /dev/sda2 as well as /dev/sdb1 and /dev/sdb2...