SAN and dbspace layout.

I shall shortly be required to create a new Informix instance using SAN disk managed by a third party. At the OS level it is looking like the SAN storage will be presented as a single disk. This will actually be striped across a number of SAN disks to be shared with other customers. I have a number of concerns as follows: 1. Separating dbspaces for performance no longer makes sense as I have lost control of which physical disks they will reside on. The only reason I can now see for having separate dbspaces is for ease of management. 2. By sharing the physical SAN disks with other customers of the third party SAN provider, performance of our application may suffer for reasons totally outside our control. I would be interested to hear experiences others have had with Informix using shared SAN storage. Are my concerns justified? Many thanks.

Desmodromic wrote: > I shall shortly be required to create a new Informix instance using SAN > disk managed by a third party. At the OS level it is looking like the > SAN storage will be presented as a single disk. This will actually be > striped across a number of SAN disks to be shared with other customers. > I have a number of concerns as follows: > > 1. Separating dbspaces for performance no longer makes sense as I have > lost control of which physical disks they will reside on. The only > reason I can now see for having separate dbspaces is for ease of > management. > > 2. By sharing the physical SAN disks with other customers of the third > party SAN provider, performance of our application may suffer for > reasons totally outside our control. > > I would be interested to hear experiences others have had with Informix > using shared SAN storage. Are my concerns justified? > > Many thanks. It still may have sense to have multiple dbspaces. For example, for faster recovery of dbspaces with most important data. Regarding performance, it seems very risky to accept that the same disks that contain your Informix databases hold other information, about usage of which you have no knowledge and that you cannot control. For example, one hot spot in the "other guy's" region would kill your performance. Also, I would pay attention to RAID configuration (RAID 1+0 is highly desirable, RAID 5 is no-no, read posts by Art Kagel). So, I would recommend RAID 1+0 configuration over physical disks that hold only your data. Darko Krstic

"Desmodromic" <davies_ms@yahoo.com.au> wrote in message news:1159849312.163378.55170@i42g2000cwa.googlegroups.com... >I shall shortly be required to create a new Informix instance using SAN > disk managed by a third party. At the OS level it is looking like the > SAN storage will be presented as a single disk. This will actually be > striped across a number of SAN disks to be shared with other customers. > I have a number of concerns as follows: > > 1. Separating dbspaces for performance no longer makes sense as I have > lost control of which physical disks they will reside on. The only > reason I can now see for having separate dbspaces is for ease of > management. Halleluljah! Somone else has seen the light! You'll get burned for heresy by some of the dinosaurs from the JBOD age on here though .... ;-) > 2. By sharing the physical SAN disks with other customers of the third > party SAN provider, performance of our application may suffer for > reasons totally outside our control. Some SANs have resource managers that limit the amount of damage any one host can do: perhaps ask your supplier if this is so on theirs? > I would be interested to hear experiences others have had with Informix > using shared SAN storage. Are my concerns justified? The first is , but it shouldn't be a concern. The second could be: I'd put it to the vendor. A good SAN with a decent cache size should give you a boost in performance, particularly if you're moving from SCSI to fibre-attached, so make sure you do ostentatiously do some tuning first, and claim the credit for yourself!

Separate ´temp dbspaces are essential, at least 3, and some logged if you have a poorly designed app (or badly trained users!) If you want to use warm restores, these work at dbspace level, so you might have issues if all your data is in one dbspace and you only want to restore a sub-set at some future time. rble pgsizes at v10) also reqi separae dbspace You don´t mention th siyze of you database, but physical splitting of logical areas will, as you mention, help with admin. (Grr Germanb Kezboards Grrrr.) How are you archiving? Ontape can get a bit funnz with very large spaces on earlier IDS versions. Keith On 03/10/06, Neil Truby <neil.truby@ardenta.com> wrote: > "Desmodromic" <davies_ms@yahoo.com.au> wrote in message > news:1159849312.163378.55170@i42g2000cwa.googlegroups.com... > >I shall shortly be required to create a new Informix instance using SAN > > disk managed by a third party. At the OS level it is looking like the > > SAN storage will be presented as a single disk. This will actually be > > striped across a number of SAN disks to be shared with other customers. > > I have a number of concerns as follows: > > > > 1. Separating dbspaces for performance no longer makes sense as I have > > lost control of which physical disks they will reside on. The only > > reason I can now see for having separate dbspaces is for ease of > > management. > > Halleluljah! Somone else has seen the light! > You'll get burned for heresy by some of the dinosaurs from the JBOD age on > here though .... ;-) > > > 2. By sharing the physical SAN disks with other customers of the third > > party SAN provider, performance of our application may suffer for > > reasons totally outside our control. > > Some SANs have resource managers that limit the amount of damage any one > host can do: perhaps ask your supplier if this is so on theirs? > > > I would be interested to hear experiences others have had with Informix > > using shared SAN storage. Are my concerns justified? > > The first is , but it shouldn't be a concern. The second could be: I'd put > it to the vendor. A good SAN with a decent cache size should give you a > boost in performance, particularly if you're moving from SCSI to > fibre-attached, so make sure you do ostentatiously do some tuning first, and > claim the credit for yourself! > > > _______________________________________________ > Informix-list mailing list > Informix-list@iiug.org > http://www.iiug.org/mailman/listinfo/informix-list >