Cross-site mirroring

[Former Member]

Hi to All,

I am planning to implement Cross-site mirroring (XSM), in order to replicate the data base for availability and protection purposes. Right now, we use a software solution for that.

I would like to know if someone that has implemented XSM can share with me some feedback, about bandwidth lines required for optimal performance, or another things that we must consider.

Regards

[Former Member]

Hi Joan,

The solution that you describe is the one that I would like to reach. I have also been considering it , but it is an expensive solution for us. By the moment I need to find a cheaper solution.

Thanks for your opinions and advice.

Regards

Eduardo Barrios

[Former Member]

Hi,

We've also replaced a software solution ( MIMIX ) for a hardware solution.

We're actually using two DS8100 storage systems attached to our i5's as iASPs. We've configured Metro-Mirror between DS8100 as a replication mechanism and we use the IBM Copy Services Toolkit as a HA application. SAP systems have been moved to this environment easily.

I think that this solution is by far better than MIMIX: it does not consume any i5/iSeries resource, there are no problems with objects out-of-sync as MIMIX had ( in our case, every day we need to resync several SAP tables ). Also with the toolkit switch times are similar than MIMIX ( 30 minutes ).

But there is only one drawback: external disk on DS8100 is slower than internal one, so you must consider the performance impact of this kind of solution. As a recommendation, do not believe IBM numbers about performance of DS8100 on i5 if they are obtained through simulation...

Regards,

Joan B. Altadill

CELSA SAP Admin

[Former Member]

Hi Victor

I agree totally with you, that is the reason because I am looking for some experiences with XSM.

Have a good weekend.

Regards

Eduardo

[Former Member]

Hi Victor,

I have taken contact with some software solution replication providers, and one of them has advised me why not XSM.

Some months ago, I remember to read a message from our friend Volker, in which he said to someone that, XSM could be a good solution.

I hope that someone of us, have implemented XSM and can share their experiences with us.

Thanks for your opinions

Regards

Eduardo

[Former Member]

Hi Eduardo,

I am not challenging that XSM could work... I just wanted to point out that some issues you have are not concerns for Mimix users. Meanwhile we are also looking for ways to lower the operation cost, but not afford of "testing" new HA solution.

Thank you,

Victor

[Former Member]

Hi Thomas,

First of all, sorry for my English and I hope I can explain to you in a clear way.

We use Vision Solution, and about how it works, I only can talk about monitoring the replication, because due technical problems with the communications company we never have done a switchover or roleswap. Only, we did a roleswap when we did a implementation test and both iSeries was in the same place, now the iSeries are in different places with a distance of 100 Km.

We have had some problems, due to remote journal locks the objects, and if you need to change the structure of some table that is locked by the remote journal, it is necessary to stop the replication. If you perform a backup in the backup iSeries, it is necessary to stop the replication too, due to the locks.

Another question is how you can manage the situation when you apply Support Packages. You cannot perform a switchover to a backup iSeries while you are applying SP in main iSeries, if in the SP there are changes to the table structures, and at least for my it is not an easy thing to know. This behavior is more or less the same with other replication tools, like Datamirror or Mimix.

The fee maintenance of Vision Solutions is 22.000€ per year, and I think that XSM is included in the OS.

One of the limitations of the XSM is that you can not use the backup machine like a file server while the XSM is active.

I have found a document about SAP and XSM, if you are interest in it, send me an email to a "ebarrios@ccc.es", and I send back it to you.

Thanks for your inputs.

Eduardo Barrios.

[Former Member]

Hi Jose,

We are using Mimix, and our experiences are a bit different...

-change the structure of some table

The transport would finish without issue. The object might be held by Mimix (rarely happens anyway), but a resync would fix it.

-perform a backup in the backup iSeries

Never an issue after Mimix V4R4 upgrade

-support package

Almost all SPs have some structure changes. We log off end users and stop the replication when applying SPs. If SP doesn't go well, we could switch the backup side in theory.

-fee

It depends on P group and CPW... It looks reasonable, considering the strong support Lakeview provides.

Thank you,

Victor

[Former Member]

Hi Jose,

which software did you use ? Are you not satisfied with it ? We get new hardware and with this we had the choise of XSM or Software. We deciede to use Vision Solution for mirroring. Its more fleible then XSM and faster to switch over.

Regards Thomas