MirrorDisk/UX How long to build a mirrored set?

[Joe Short]

I have a client that is planning to move off of direct attached storage to SAN attached. They would like to use MirrorDisk/UX to mirror from device to device. The thing is, they would like some idea as to how long it may take to accomplish. Does anyone have a reference that may provide a rough estimate of how long it takes to mirror a fixed amount of data? I'd like to use it to roughly estimate the time required to get the job done.
I am not looking for exact numbers, just a rough estimate.

Thanks.

[Rick Garland]

This is based on the throughput of network (copper vs fiber), disk throughput, IO throughput in general, system load, etc.

Lots of variables. Can get a rough estimate by doing a couple of medium sized files (say, 2 GB in size) and extrapolating the time from that.

[RAC_1]

Mirror disk is good for mirroring root disk. The mirroring of the data you access from SAN, is mirrored on SAN itself and it can be set to do diff. raid levels. The SAN provides hardware mirroring and is quite fast in camparsion to the mirror disk (software mirroring)

So depending upon what SAN you connect, set your raid levels and SAN itself takes care of mirroring the data.

Anil

[Peter Godron]

Joe,
too many factors:
1. Are you syncing within the SAN or talking about initial transfer from direct storage to SAN?
2. Disk speed and network transfer speed.
Can you please clarify.
Regards

[eran maor]

Hi Joe

doing the mirror dep. on how much data you have on the disk .

you need to understand that mirrorDisk/UX is Mirroring onlt logical volume and not disk .

so the commands are to do pvcreate on the disk , vgextend the disk and to run the lvextend -m command .

i did a mirror of 8 logical volume with 40 g.b and it took me 2 hours , but i was working with kinston system , just to see a sample of much it will take to mirror your system.

eran maor

[Joe Short]

I am synching from a direct attached 1GB fiber channel array to a SAN attache 2GB fiber channel storage.
I need to provide a general scope so I can estimate the time needed and cost of my time.
I do not need exact numbers, just a rough enough estimate to show some sort of value/price.

[Geoff Wild]

I would set up a test - then measure the time it takes to mirror.

There are way too many factors to estimate...you are looking at minutes to hours - depending on the amount of data - if you are going to do multiple mirros at the same time...etc...

Rgds...Geoff

[Joe Short]

A test is not possible. I need to price the job, and win it before I can get to the environment.

[Geoff Wild · Accepted solution]

How much data?

We did some mirroring in a recent san migration - took around 8 hours for about 2 TB...

Rgds...Geoff

[Joe Short]

Geoff, was that on a single server or several? I have 3 servers here, and am still waiting to get the total storage figures and how it is assiggned to the servers from the client.

[Peter Godron]

Joe,
the figures so far:
eran 40Gb in 2 hrs
Geoff 2Tb in 8 hrs
So you can see no valid estimate is possible.

If you are going to use mirroring to get the data from direct storage to SAN, does it matter how long it takes,as the disks are going to be available at all times and the SAN disk will stay in sync after the copy.
Or am I missing something?
Regards

[Joe Short]

It only matters in the proposal the client wants. They want to know about how long it will take and how much it will cost for me to do.

[Geoff Wild]

It was a single server - and it was done on the weekend - when the database was quiet - but not down...there was no other activity going on the "new" frame....
Your results may vary :)

Rgds...Geoff

[Geoff Wild]

UPDATE - just found the old log - we split the job in two - did 1TB first - then the 2nd after - sequentially - so it actually took almost 16 hours....

Rgds...Geoff

[Florian Heigl (new acc)]

Joe - have them supply the sustained throughput of the DAS, without You're just getting Yourself into trouble, because they'll be able to hold You responsible if they have errors in their setup. That's sheer madness.

To give You a rough indicator - calculate 75% protocol speed for the DAS, the SAN side should be much faster, unless of course it's shared between many highly loaded hosts.

[Florian Heigl (new acc)]

Also have a look at the second reply in this thread:

http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=811185

[Joe Short]

Well, I'll just guestimate at about 40GB per hour, and hope for the best.
At least I can put some numbers on paper.