state database replicas

[kahn630]

What is the min slice required to create disk suite metadb replica, and also can I create two replicas on the same slice, if yes then what are the pros and cons creating multiple state database replicas on the same slice vs each replica on different slice .....thanks

 

[cndcadams]

Kahn;


look at this pdf,

http://docs-pdf.sun.com/805-5962/805-5962.pdf

page 8.


It will answer your questions.

Thanks

CA

 

[cndcadams]

Also check out this doc, it is a quick guide setup for boot disk mirroring, I have used it and works fine.

http://www.sun.com/bigadmin/content/submitted/svm_mirroring.html

Thanks

CA

 

[Annihilannic]

If you have a few disks in your system then I don't see the need to put multiple state database replicas on one slice. If you only have a couple of disks though it may be an idea, just in case one of the blocks containing the state database goes bad.

I think about 4-5MB is usually enough, although on the last system I set up it seems I used about 20MB.

Annihilannic.

 

[KenCunningham]

I think Franz has commented on this increased requirement (Solaris 9?) in another thread, but I haven't been able to find it.

 

[daFranze]

yes, afaik SDS 4.2.1 has larger state DBs than 4.2, I usually spend 30 MB for 3 copies in one slice

Best Regards, Franz
--
Solaris System Manager from Munich, Germany
I used to work for Sun Microsystems Support (EMEA) for 5 years in the domain of the OS, Backup and Storage

 

[marrow]

I've used 32Mb on a 36GB HDD, not sure who advised. Don't see any point in 2 x metadbs on the same slice, although Sun do recommend 3 metadbs as a safer bet than using only two (see man metadb) in total.

 

[daFranze]

SDS/SVM needs at least 3 statedbs to start and (n/2)+1 of all configured dbs. In the old days when you had only two disks, or in small servers with just 2 disk slots, it makes sense to have 3 dbs in one slice to have at least 3 dbs intact if one disk fails...

Best Regards, Franz
--
Solaris System Manager from Munich, Germany
I used to work for Sun Microsystems Support (EMEA) for 5 years in the domain of the OS, Backup and Storage

 

[Annihilannic]

I have a niggling memory of some special write option (synchronous perhaps, i.e. confirming successful write to both mirrors before returning success) that could be enabled for DiskSuite which was safer for databases, but can't find anything that sounds right.

The only thing close that I have found is the 'metainit -S' option for serialisation of writes, although I'm not sure how much of a benefit that would be; it would presumably have a significant negative impact to write performance.

Annihilannic.

 

[Annihilannic]

Oops, wrong thread.

Annihilannic.