IBM RS6000 F50 problems 1

[Voja]

Hello all
I have "few" questions about AIX system on this kind of machine.
How to mount a floppy diskette as a file system? What kind of file system should be on that diskette so it could be recognized by aix?

Recently I changed battery on scsi fast cache card. I found how to reset battery counter, but it seems that cache card is disabled somewhere. Where can I enable it and how it was disabled (by someone before I took place of a system admin)?

Is it possible to expand ssa raid5 array without destroying an existing array and data on it (adding + rebuilding)?

 

[madmurdock]

1) Usually you do not mount a floppy like on Linux systems. Whether you just tar and untar a file to and from the floppy, then the aim is /dev/fd0, or you use the dosread and doswrite commands, which will you be able to write and read a DOS-formatted diskette. These commands you will fgind in the bos.dosutil installp

SCSI-card: no clue
ssa-raid: no clue

greets

mad_murdock

 

[Voja]

Thank you for your fast reply. You noticed well - I am a Linux user and got used to it. This totally confused me when I saw that I can tar to floppy or eventually "flcopy" a file but only one file under name "floppy". The problem was that I needed to save microcode for ssa disks, because I got a new supply of ssa disks and that's how I got to second problem - expanding an existing raid array.

 

[petertp6]

AIX does not support mount /dev/fd0 as a filesystem.
you can only use dosread,doswrite,dosformat to deal with floppy.

 

[bi]

Regarding expanding the existing RAID5 array:

Just create another separate RAID5 array device, then add that new hdisk device to the logical volume that holds the current RAID5 device, then either extend the logical volume followed by extending the filesystem (this allows you to specify to which disk the filesystem will be extended), or just extend the filesystem.

I recommend extending the logical volume first, especially if the filesystem is part of a database.

 

[bi]

And, I forgot to add: no, you cannot add another disk to the existing RAID5 array without destroying the existing data. That is why you have logical volume manager: so you can add another device to the logical volume and enlarge a filesystem that way.

 

[Voja]

Thank you all for your response. In the meanwhile (while waiting for the response), I eventually DID what you suggested - I found a "backup a volume group" option, made a backup, destroyed a vg and rebuilt it from the tape...

 

[bi]

Why? You didn't have to do that with the capabilities of logical volume manager, unless you didn't have enough disks to create a new RAID5 array to add to the volume group?

 

[Voja]

Well, as you said, a new array would be a 1 more disk less, which is too much, and I also needed to make an exact match to one other machine, which has 9 ssa hdd in raid5 chain. Btw, from system's "point of view", if I have 2 chains instead of 1 like the other machine (primary server and secondary server are here in question) could I restore files from primary without too much trouble? I mean 1 chain vs 2 chain?
How much am I losing in performance by enlarging that raid chain instead of making another one?

 

[madmurdock]

If you still need to write your Microcode-savings to a floppy-disk, just execute:

tar cvf /dev/fd0 /usr/../microcode1 /usr/../microcode2

this will save all the microcode versions in a tar format on the floppy

 

[bi]

An array can only be made in one loop -- you can't take disks that are in one loop and use them for an array in another loop.

If you have two loops, you have two arrays. The filesystem doesn't care if you have the RAID arrays in one loop or two, as long as the filesystem is large enough to hold the data. You might be losing a little in performance, but not enough to justify downtime to change it.