Re: Informix Mirroring

Thank you both Art and Eric for your input on informix Mirroring. have a great day. --Dave On Wed, Feb 3, 2010 at 3:57 PM, Art Kagel <art.kagel@gmail.com> wrote: > On performance, Informix's testing back in the 90's showed that > hardware/firmware mirroring was fastest followed by OS level software > mirroring, followed closely by Informix's mirroring. The main reasons to > use IDS's mirrors are twofold: > > - Convenience. You don't have to depend on SAs to manage your mirrors. > - Some internal performance gains from parallel reads where IDS has > intelligence that the OS or a SAN doesn't. - Normally this is not a big > gain. > > On the other issue, something isn't documented properly. As long as there > is an active primary or mirror chunk the engine will stay online. > > Art > > Art S. Kagel > Advanced DataTools (www.advancedatatools.com) > IIUG Board of Directors (art@iiug.org) > > See you at the 2010 IIUG Informix Conference > April 25-28, 2010 > Overland Park (Kansas City), KS > www.iiug.org/conf > > Disclaimer: Please keep in mind that my own opinions are my own opinions > and do not reflect on my employer, Advanced DataTools, the IIUG, nor any > other organization with which I am associated either explicitly, implicitly, > or by inference. Neither do those opinions reflect those of other > individuals affiliated with any entity with which I am affiliated nor those > of the entities themselves. > > > > On Wed, Feb 3, 2010 at 1:04 PM, Dave <in4mixdba@gmail.com> wrote: > >> Hello, >> >> I was reading up on Informix Disk/Chunk Mirroring and was wondering if >> anyone has any experience using Informix mirroring versus O/S or >> Hardware mirroring relating to performance? >> >> Also, is this a typo in the Informix documentation for mirroring? >> >> See the sentences, "On the other hand, when an mirrored chunk goes >> down, the database server cannot access the data stored on that chunk. >> If the chunk contains logical-log files, the physical log, or the root >> dbspace, the database server goes offline immediately." >> >> Can that possibly be ? >> >> Here is the link to the source Doc: >> >> http://publib.boulder.ibm.com/infocenter/idshelp/v115/topic/com.ibm.admin.doc/ids_admin_0799.htm >> >> Full Text: >> Consequences of Not Mirroring >> If you do not mirror your dbspaces, the frequency with which you have >> to restore from a storage-space backup after media failure increases. >> >> When a mirror chunk suffers media failure, the database server reads >> exclusively from the chunk that is still online until you bring the >> down chunk back online. On the other hand, when an mirrored chunk goes >> down, the database server cannot access the data stored on that chunk. >> If the chunk contains logical-log files, the physical log, or the root >> dbspace, the database server goes offline immediately. If the chunk >> does not contain logical-log files, the physical log, or the root >> dbspace, the database server can continue to operate, but threads >> cannot read from or write to the down chunk. If an unmirrored chunk >> goes down, you must restore it by recovering the dbspace from a >> backup. >> _______________________________________________ >> Informix-list mailing list >> Informix-list@iiug.org >> http://www.iiug.org/mailman/listinfo/informix-list >> > >