[BC] RAID servers

[Cowboy]

On Friday 27 March 2009 04:21 pm, towers at mre.com wrote:
>  On our HP file servers, we tried RAID 1 (mirrored). We lost a drive and
>  the machine became a door stop when we tried to install a new drive and
>  have it reformat. It took a complete reload of the OS and reconfigure to
>  bring it back to life.
>  
>  RAID isn't all it's cracked up to be when used as a C drive......

 Hardware RAID and windows machines, I'd tend to agree. 
 It's overrated.
 Depends on the controller, though. 
 Some, the disk can be plugged into the IDE buss and used as
 a single disk, others use proprietary formats, so that the disk
 can ONLY work with that controller.
 I prefer the former. If the controller fails, at least any of the
 disks *can* work stand alone. ( RAID-1 and the like, not RAID-0
 or RAID-5 )

On Friday 27 March 2009 05:36 pm, Jerry Mathis wrote:
>  I don't claim to be a RAID expert, but I've always understood that a RAID
>  array holds DATA ONLY, or at least NOT the OS. The C: drive should be a
>  SEPARATE drive. I can understand how RAID wouldn't work if the OS and
>  program in ON the RAID drives.

 No, the array appears as a virtual drive to the system.
 It behaves the same as any other single hard drive, with some
 additions, and caveats.
 There's no GOOD reason to NOT have the system on a RAID array.

 For me, my machines run data-journaled EXT3 filesystems on software
 RAID-1 arrays. The system checks the health of the array every hour,
 so I'd go at most 59 minutes after failure of any disk before I know about it.
 Further, either disk can run stand alone if necessary.
 It's saved my hiney a couple of times.

 By using Linux software RAID, which is partition based and not device based,
 I have two completely redundant boot drives with the complete system
 and data on the array, so that I can lose any one partition, and specific combinations
 of two partitions simultaneously, and keep running.
 Power can fail at any point during disk reads, or writes, and the entire system
 will auto-recover as if the failure never happened.
 True, if the A drive fails, the system will need manual intervention to boot, but
 otherwise auto-boot as well as everything else just continues to run, while
 complaining loudly about the failure.
 Additionally, backups to another machine are also automatic, in the event of
 a motherboard failure, against which RAID can not protect.
 My systems suffer hardware failures the same as all of them do, but I do not
 lose data anymore.

-- 
Cowboy