Re: ASM and VMWARE

You want to be using shared VMDK for your ASM storage if possible. Whilst you can use LUN's passed through from the SAN (known as RDM storage in VMWARE) it can introduce limitations around what VMWare features you can use (vmotion, snapshots etc).

We also observed strange problems when extending single RDM LUN's where ASM does not like the mismatch in size between instance and will trigger an eviction.

My recommendation would be to go with shared VMDK (start with 4 x shared VMDK based on how much  storage you need) and then extend your storage by adding VMDK to the disk group as you go.

Your admin can assign a single LUN to the VMware datastore which will simplify things on the storage management side. On Jun 15, 2024 at 5:50 AM +1000, Ed Lewis <eglewis71_at_gmail.com>, wrote:
> Yes, I'm familiar with that.
> I'm looking for some real life experiences.
>
> Thanks again
>
> On Fri, Jun 14, 2024 at 3:16 PM dougk5 <dougk5_at_cox.net> wrote:
> >
> > VMWare has a best practices guide for Oracle that you can find with a web search.
> >
> > Doug
> >
> >
> > On Fri, Jun 14, 2024 at 12:10 PM, Ed Lewis
> > <eglewis71_at_gmail.com> wrote:
> > Thanks Osman.
> > I'm familiar with the information you provided, but I would like to know if
> > these same guidelines apply to VMWARE, and EMC.
> >
> > Thanks again.
> >
> > ed
> >
> > On Fri, Jun 14, 2024 at 3:02 PM Osman DINC <dinch.osman_at_gmail.com> wrote:
> > > >
> > > > Hi Lewis,
> > > >
> > > > Oracle recommends using four (4) or more disks in each disk group. Having multiple disks in each disk group
> > > > spreads kernel contention accessing and queuing for the same disk.
> > > >
> > > > https://docs.oracle.com/cd/E11882_01/server.112/e10803/config_storage.htm#HABPT4790
> > > >
> > > > The number of LUNs (Oracle ASM disks) for each disk group should be at least equal to four times the number
> > > > of active I/O paths. For example, if a disk group has two active I/O paths, then minimum of eight LUNs
> > > > should be used. The LUNs should be of equal size and performance for each disk group.
> > > > An I/O path is a distinct channel or connection between storage presenting LUNs and the server. An active
> > > > I/O path is an I/O path in which the I/O load on a LUN is multiplexed through multipathing software.
> > > > Ensure that all Oracle ASM disks in a disk group have similar storage performance and availability
> > > > characteristics. In storage configurations with mixed speed drives, such as flash memory and hard disk drives
> > > > (HDD), I/O performance is constrained by the slowest speed drive.
> > > >
> > > > https://docs.oracle.com/en/database/oracle/oracle-database/19/ostmg/considerations-asm-storage.html#GUID-18D7AFB2-F417-4E1F-B3B0-02585E385818
> > > >
> > > > Multiple ASM disks allow for multiple I/O queues in the OS, and so can assist with performance. However
> > > > too many disks may prove cumbersome to manage.
> > > >
> > > > Regards,
> > > > Osman DİNÇ
> > > > https://dincosman.com
> > > >
> > > >
> > > > Ed Lewis <eglewis71_at_gmail.com>, 14 Haz 2024 Cum, 21:57 tarihinde şunu yazdı:
> > > > >>
> > > > >> Hi,
> > > > >>
> > > > >> I recently took on a project with a new client.
> > > > >>
> > > > >> I’m tasked with building several databases in a RAC environment (19.23)
> > > > >>
> > > > >>
> > > > >>
> > > > >> ASM is being used with VMWARE on a EMC Unity Array. I recommended
> > > > >>
> > > > >> creating a few disk groups with a minimum of 4 LUNS (same size) for each group.
> > > > >>
> > > > >>
> > > > >>
> > > > >> The unix admin is against doing that saying that just use 1 large
> > > > >> disk for each group.
> > > > >>
> > > > >> He says it’s a disadvantage when using a virtual disk infrastructure
> > > > >> like we have with our EMC Unity disk farm.
> > > > >>
> > > > >> He states it is actually a disadvantage to carve up such small
> > > > >> physical disks at the SAN Storage Array processor
> > > > >>
> > > > >> level and is not actually even possible as only whole disks can be
> > > > >> assigned to a particular use at that level.
> > > > >>
> > > > >>
> > > > >>
> > > > >> Although, I have not worked much with VMWARE, I’ve never heard of
> > > > >> these restrictions
> > > > >>
> > > > >> when using ASM, so I have my doubts.
> > > > >>
> > > > >> Any thoughts or experiences on this would be greatly appreciated
> > > > >> --
> > > > >> http://www.freelists.org/webpage/oracle-l
> > > > >>
> > > > >>
> > --
> > http://www.freelists.org/webpage/oracle-l
> >
> >
> --
> http://www.freelists.org/webpage/oracle-l
>
>

--
http://www.freelists.org/webpage/oracle-l