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16 nagger commented Permalink

Hi alpharob1, <br /> Sorry I can't comment on SSP and Easy Tier interference because I don't know about how Easy Tier works. I am flattered that you think I am an expert on everything. Reminds me of my first day at IBM when I went to tune an early AIX system and the customer wanted me to fix a IBM Golfball typewriter :-) Your idea seems completely crazy IMHO and cuts totally across the maximum I/O rate by spreading every LU across every LUN in the pool. I think a LUs spread across say many tens of LUNs and so across 100's of disks with V7000 caching is going to out perform any LU downgraded to a simple collection of NPIV LUNs without East Tier but could be interesting switching on Easy Tier - I would not bet on the results. But more importantly SSP will scale. Perhaps, we will get to benchmark that some day - say 500 hundred NPIV LUNs against 500 SSP LUs. You are also trying to micro-manage disk space that is so ultra high man-power "old school" - a button to convert SSP to dedicate NPIV LUNs is exactly what we don't need for the future. With a SSP supporting many hundreds virtual machines, I don't think its a option, anyway. It is good to have a debate and a long think about these alternatives. <br /> Cheers Nigel

17 joyama commented Permalink

Hi, Nigel, SSP4s Performance is very great! <br /> By the way, since in the event of a failure of the VIOS, to ensure the mirror write consistency, what technology do you use to SSP4? <br /> Technology similar to MWCC of LVM mirroring Do you have a built-in SSP4?

18 nagger commented Permalink

alpharob1 - Jan 28 <br /> I think you have forgotten that the SSP allocates "chunks" of disk in 64 MB units but the disk I/O is still done are the 4KB level or larger if the application does larger blocks. A busy VM will create busy regions in the SSP LUNs and Easy Tier will kick in. I don't think we need further magic and the LU spread across every LUN in the pool is exactly what I want for maximum performance.

19 FlorentMairesse commented Permalink

Hi Nigel <div>&nbsp;</div> Does SSP4 supports hdiskpower from EMC VPLEX ? <div>&nbsp;</div> we can't add or replace any hdiskpower <div>&nbsp;</div> $ pv -add -clustername clpurb1 -sp sppurb1 hdiskpower397 <br /> get_other_disk_uuid: Device hdiskpower397 is an unsupported third party device. <br /> register_other_disk: Could not create a disk UUID for device hdiskpower397. <br /> ERROR: Specified device, hdiskpower397, is not a supported type. <br /> chcluster: One or more of the given entities is invalid. <br /> PV could not be added to cluster, check PV and cluster status. Also check for network connectivity issues <br /> hdiskpower397 <div>&nbsp;</div> CAA: Invalid input parameter. <div>&nbsp;</div> Please check the parameters. If the parameters are valid, the error <br /> may be due to configuration or cleanup issues. <div>&nbsp;</div> If these issues cannot be resolved, please collect debug data and contact <br /> Service Representative for further assistance.

20 nagger commented Permalink

Hi Florent Mairesse, I am told any disk type that is supported by the Virtual I/O Server (VIOS) is also supported for Shared Storage Pools. So that is the check you need to make. For most non IBM disks, the last time I looked you may find that IBM refers your to your Disk Vendor - it is after all them that decides if VIOS is a supported environment. I know that some EMC disk types are support - I just don't know about the EMC VPEX or the version or device driver options. This goes for any disk vendor.

21 AchimScreen commented Permalink

As I think about to start with SSP, I can't see an opportunity to differenciate several modes in one SSP. For example: <br /> - set 1 are DS8K with failure groups over two storage boxes (site mirroring) <br /> - set 2 are NetApp unmirrored <br /> - set 3 are some production LUNs mirrored over two NetApp boxes <br /> I was told, that should be possible with TIERs, but googling about shared storage pool tiers, I find no usefull information <br /> So do I have to use a storage pool with a fixed attribute (either mirrored or unmirrored, either DS8K or NetApp - as we don't want to mix them) ? <br /> Or is (or will) there be some mechanism to differenciate these attributes in the storage pool ?

22 Daniel Bevilacqua Meireles commented Permalink

Hi Nigel, how are you? <div>&nbsp;</div> You said "in SSP4, the read I/O is only done on one mirror copy, so it is the same speed as no mirror". My question is: is there a way to tell the SSP which Failure Group to use when perform a read I/O? Something like the "sequential mirroring" used by AIX, when there is a distinct primary copy and secondary copy and reads are done using the primary copy? <div>&nbsp;</div> Best Regards!

23 nagger commented Permalink

Daniel Bevilacqua Meireles - There is no way to specific the preferred mirrored copy to read. I suspect that a future release will use both mirrors. There is no primary or secondary copy they are both the same.