[ABANDONED] System rescue with hardware RAID

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[ABANDONED] System rescue with hardware RAID

Postby ychaouche » 2016-03-01 09:37

Hello !
I had a RAID problem on an HP Proliant server due to a failing disk. When I changed the disk, things got complicated and RAID seemed to be broken. I put back the old disk, repaired the RAID, then changed put the new disk again and all returned to normal except the system doesn't boot. I am stuck at grub stage (the grub rescue prompt). I grabbed a netinst CD and tried to rescue it, at some point, the wizard correctly sees my two partitions sda1 and sda2 and asks wether I want to chroot to sda1 or sda2. I had red screen errors on both. The error message said to check syslog, syslog says can't mount EXT4 file system beacuse bad superblock. I switched to TTY2 (Alt-F2) and tried fsck.ext4 on sda1 (I think sda2 is the swap because when I ran fsck on it it said something like this partition is too small and suggested that it could be swap) it says bad superblock and bad magic number. I tried e2fsck -b 8193 as suggested by the error message but that too didn't work (I think the -b 8193 is for trying to get he backup superblock).

Any suggestions on how to further investigate this ?

The RAID is as follows : One RAID array of 4 physical disks that are grouped into one Logical Volume /dev/sda, so the operating system only sees one device instead of four (4 disks).
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Re: [ABANDONED] System rescue with hardware RAID

Postby ychaouche » 2020-11-05 12:46

Couldn't find a solution, had to re-install everything.
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Re: [ABANDONED] System rescue with hardware RAID

Postby CwF » 2020-11-05 15:16

The extra dependencies and non-KISS nature of raid is useless in today's commoditization. Storage can be chained without any failure modes depending on the other members or special hardware. Raid has no compelling features since it doesn't take a stack of disk to saturate the bus anymore. Now we should mirror the entire machine, and make those machines as simple as possible.
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Re: [ABANDONED] System rescue with hardware RAID

Postby LE_746F6D617A7A69 » 2020-11-07 21:17

CwF wrote:Raid has no compelling features since it doesn't take a stack of disk to saturate the bus anymore. Now we should mirror the entire machine, and make those machines as simple as possible.
???
Do You mean Virtual Machines? If so, then yes, nobody is creating VMs with RAID capability - but the underlying storage system, which holds the VMs virtual disks is always a RAID system, at least a cheap RAID1.

If by "mirroring machines" You mean hot standby, then again, Your claim is not valid, because hot standby machines needs to be synchronized in realtime, to assure that the standby machine has all the data synchronized with the primary machine (otherwise it couldn't be used as a hot spare). There are only 2 possible methods to achieve this: both machines are using the same RAID-based storage system (most efficient method) or the storage systems of primary and hot standby system are synchronized at a higher level, like a database mirroring, which is slow like hell when compared to RAID ;)

Another thing is that You have not specified what do You mean by "saturating the bus" - do You mean PCI-E x8 v3.0 (8GB/s)? - none of SSDs and of course none of HDDs can saturate this bus without using RAID.
Bill Gates: "(...) In my case, I went to the garbage cans at the Computer Science Center and I fished out listings of their operating system."
The_full_story and Nothing_have_changed
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