Stripset on HSG80

[Ivan Ferreira]

Remember that you need a minimum of four disk to create a RAID 0 + 1.

The disks should be the same size.

[generic_1]

Raid 5 might save you a little space, but 0 + 1 is a good raid option and is a bit faster normally because it does not have to calcualt parity like raid5.

[Ian Derringer]

What would be my mirror raid option with only 2x72GB hard drives? I do not like raid5 because of the seek time. Any other ideas?

Thanks so much!!

Ian

[Ian Derringer]

From what I read, RAID 1 is what I can do with 2x72GB or RAID5....Am I correct? I know RAID0+1 would be ideal, but the hardware is not feasible at this time. However, I do want redundancy though.

I do appreciate all the kind advice & wisdom.

Ian D.

[Uwe Zessin]

With 2x72GB, you can do RAID-1, but not RAID-5. RAID-5 requires at least 3 disk drives (2 data chunks combined give you a parity chunk).

On the HSG, you need at least 4 disk drives to implement striped mirrorsets (some call it RAID0+1, other call it RAID1+0 - depends from which layer you look...). For this you create two mirrorsets (RAID-1) and put a stripeset (RAID-0) on top of it. E.g.:

> add mirrorset M101 DISK10000 DISK20000
> add mirrorset M102 DISK30000 DISK40000
> add stripeset S100 M101 M102
> initialize S100
> add unit D1 S100 disable_access_path=all


You can use single-member mirrorsets now and expand them later:

> add mirrorset M101 DISK10000
> add mirrorset M102 DISK30000
> add stripeset S100 M101 M102
> initialize S100
> add unit D1 S100 disable_access_path=all

Later:
> set M101 nopolicy
> set M101 member=2
> set M101 replace=DISK20000
> set M101 policy=best_performance
> set M102 nopolicy
...

[Ian Derringer]

This is write-up on how to create stripe mirror on HSG80 - Thank you!!

What are some of the steps do I need to do for RAID1??

Again, I do appreciate all the help!!

Ian D.

[Uwe Zessin]

Just for 2x 72GB disks?

> add mirrorset M1 DISK10000 DISK20000
> initialize M1
> add unit D1 M1 disable_access_path=all

You need to assign a unique 'identifier' to the unit which is responsible for the OpenVMS unit number, e.g. for $1$DGA17:

> set D1 identifier=17

Verify with:
> show id


Access to the unit depends on which host request access - I would look up the connection names from an existing unit.

> set D1 enable_access_path=(n1, n2, ...)

[Ian Derringer]

Got it!! Super!

I will assign by using the previous identifier number $1$dga13

Once again, thanks for all your help!

Ian D

[Uwe Zessin]

I think you have to reboot the server or run REPLACE_WWID operation in SYSMAN, because the unit now has a new WWN (600...).

[Ian Derringer]

Since I am working within VMS, all I have to do is run mcr sysman auto io and that should be it.

Would it be okay for me to create stripe mirror over the RAID-1 I created now once I have more drives??

Ian D.