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Extending a RAID array in a 4354R enclosure on MA8000

Jeremy Stephens
Occasional Advisor

Extending a RAID array in a 4354R enclosure on MA8000

I have inherited a Compaq storageworks MA8000 with two HSG80's and three 4354R disk enclosures. I have the task of setting this up and I have a question. If I have for example three drives in a RAID 5 config and another three drives in a RAID 5 config and I need to add another drive to the first RAID 5 config does it have to be a concurrent drive or can the drive be anywhere in the array and be added to a RAID 5 config. I hope this is clear.

Thanks,

Jeremy
3 REPLIES
Mike Naime
Honored Contributor

Re: Extending a RAID array in a 4354R enclosure on MA8000

To answer some of your questions.

Since you did not specify the OS that you are using with the HSG, I will assume that
You will be using the serial console cable to connect your laptop to the HSG80 CLI. (Do you know where this is?)

a.) On the HSG80, you cannot dynamically expand a raidset. you would have to delete the existing UNIT and STORAGESET (RAIDSET) before you could remake the raidset with 4 spindles. Then you must initialize the storageset, and remake your unit.


ex.
DEL D21
DEL R21
Add raid R21 disk10000 disk20000 disk30000 disk40000
init R21
Add unit D21 R21 {DIS=all}
SET D21 ID=???
SET D21 ENA={Connection names}


Note: If you only have 3 shelves (SCSI CHANNELS) you can only make a 3 drive raidset if you are paranoid about loosing a channel and loosing your raidset. If you do not care about this... you can make up to a 1TB raidset.

In your case, you would hopefully have a spindle from channels 1, 2, and 3 in the existing raidset. SHOW STORAGE or SHOW RAID should show you the information that you require to see what is in the existing storage sets.

What you might want to consider (If you have enough spindles available), is to create a new raidset. Present this to your current server(s) and transfer your data to the larger raidset.
VMS SAN mechanic
Jeremy Stephens
Occasional Advisor

Re: Extending a RAID array in a 4354R enclosure on MA8000

It will be on windows 2000. Nothing is configured yet. In fact I have to order Hard drives for it. I am just gathering prelimanary information before I tackle it. I have the MA8000 with two HSG80 controllers, the Arrays are 4354R drive enclosures, each holds 14 drives. There are two channels to each enclosure. Basically I want to see if I could dynamically add a drive to a RAID set if I needed to but from what I see from your response this is not possible, I would have to recreate the set there for I would have to recreate my data on that set. I have not set anything up yet so I assume the best avenue is to make the RAID set big enough for future expanson. I still need to know though if you do need to add a drive to a RAID set, hence recreating the RAID set, does it have to be the next consecutive drive? I assume it does.
On the note portion of your response. Since each enclosure has two SCSI Channels, am I limited to the number of disks in a RAID set on that enclosure? Each enclosure has 14 drive bays, so could I not have a RAID 5 config with 5 drives and then another RAID 5 set with 7 drives and then two HS drives on that one enclosure (4354R)?

Thanks,

Jeremy
Mike Naime
Honored Contributor

Re: Extending a RAID array in a 4354R enclosure on MA8000

With the Information that you have given in your last post, I would say that you want to look at making CONCATSETS to allow for future expansion of your "Raidsets". Since this is not somethign that is already in existence, you can do this. Basically the concatset allows you to stripe your raidsets into a larger volume.

You would make your raidset. INIT. Put the raidset into a concatset. Make the unit from the concatset. Then at a later date, you could add another raidset to the concatset.

Limits on Concatsets. (8.6 manual)
No Mirrorset.
No Partitions.
Up to 24 spindles.
No CLONE.
No remote copy sets.


If you have the dual channel enclosures, (7 drives per channel) you can make the raidsets up to 6 drives each without exposing yourself to a bus failure.


Something that I would not want to test on a live system would be to take an existing raidset. Delete the unit. Make a concatset from the raidset. Make a unit from the concatset. See if it trashes the data.
VMS SAN mechanic