Does LVM offer any sort of fault tolerance redundancy ?

[Yaboto]

Hi,

I have an RX2620 server with no smart array. All the 3 internal disks channels A & B are connected directly to the mother board. The customer wants to take maximum advantage of the total size of the 3 disks and at the same time provide a minimum level of redundancy such as one disk failure should not interrupt the production.
How can I do this ?

Regards,
Berag

[TTr]

With LVM you need the optional add-on product Mirrordisk/UX to be able to create mirrored volumes on the disks. This way you could get the equivalent of 1.5 disks of usable space.

[Mel Burslan]

The feature you are looking for is the RAID functionality which is provided by certain types of RX class machine hardware (as an optional feature) I am not sure about RX26xx series but considering the capacity of these machines (they are basically unix workstations) I don't think RAID is an option available to those. Your next best bet is Mirror UX (which is a add on product until HPUX 11.23 versions but included in some/all bundles on V11.31) but with 3 disks, you need to do some creative mirroring yourself, manually to distribute the mirror extents and such.
Best bet is to offer your customer to contact HP to investigate what options they have available to them along with the pricing of those options.

[Torsten.]

IF you want to have maximum space + redundancy you need to get a 640x smartarray and create a RAID 5. Otherwise you can use LVM and create a mirrored pair (2 disks) only.

[Jozef_Novak]

If you go for the MirrorDisk solution, the best you can do with 3 disks without jeopardizing data is to create a 2-way mirror. In this way you will create a second copy of your data on the third disk for additional redundancy. Alternative would be to use the third disk for some low important, non critical data, which you can afford to lose.

J.

[sujit kumar singh]

Hi with the MirrorDisk/UX prpoerly configured so that you mirror the LVs on the separate disks and also that disks staying on separate HBAs you get disk as well as the HBA level redundancy.


Regards
Sujit

[Yaboto]

Hi,

Thanks for all your replies.
The customer has 300GB*3Disks= 900GB. He doesn't want to purchase any smart array for RAID5, he doesn't want to purchase any license for HP-UX Disk Mirroring. He wants a usable space of at least 600GB, and an overhead for fault tolerance redundancy of 300GB maximum.
Is that possible ? Is there any way to do that ?

Regards,
Berag

[Mark S Meadows]

Hi Berag,

The practical solutions are as have already been suggested above.

My tact would be to guide the customer that they need to at least invest in Mirror HP-UX and if possible a couple of smaller additional internal disks (2 x 70GB) for mirroring the operating system. Utilising 300Gb disks for all/part of the O/S is a bit of a waste and better used for the application data.

The 300 GB disks could then be better utilised.

Some times you need to spend a bit money in order to invest in the future.

Regards,

Mark

[TTr]

You can not do it with what you have and without buying either a RAID controller or LVM mirroring. Have you or your customer heard the expression "you want to have the pie and eat it too?"?

If you change from LVM to BaseVxVM (no cost)then you can use mirroring but ONLY for the basic OS vlumes such as /stand, SWAP, /, /tmp, /opt, /usr, /var. You can not mirrror any additional volumes so all your additional software installs and data have to be created probably under /opt.

[Torsten.]

It depends on what you have - some OE versions (bundles) have the mirroring already built-in as a part of the basic OS.

Best to check if you have the "-m" option in lvextend.


Without *any* kind of mirroring you cannot have redundancy.


BTW, I cannot calculate this:

600 GB data <==> 300 GB for redundancy ???

This means 300GB have no redundancy, right?

[Yaboto]

From your different replies, I think I have to convince the customer to buy a Smart Array Card or a license for HP-UX MIRRORING.