Storage allocation methods

Storage architecture
Storage arrays
My current employer began allocating disk before having a storage administrator on staff. When a file system would achieve 90%, the individual systems admins would log on and just assign themselves new LUNs. This has made layout of the disk a nightmare. One thing they have done - in the name of "performance" - is to spread LUN assignment across multiple fibre ports (FAs, CHIP ports, etc.) on the array. For example, using EMC nomenclature, if a server were getting 2 terabytes of SAN disk, 500 GB of it would go on FA 4A, 500 GB would go on FA 4B, another 500 GB on 4C and the final 500 GB on FA 4D. All of their Unix servers are done this way. This is how they were spreading the IO load on the array's ports. However, other than telling them it makes administration a nightmare, I can't come up with a compelling reason for them to migrate the existing systems to consolidate their servers to single ports on the array. Is there some information somewhere that can help? The systems are HP-UX 11i v1 and the array is an HP XP1024 with 12 CHIP ports per fabric, 8 of which are expressly for Unix. Thank you so much.

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Your Unix admins will not want to do this… and rightly so. Striping the LVM volumes across multiple ports increases the performance. Having multiple LUN’s under HPUX also increases the SCSI queue depth for greater performance in high IO load (OLTP) type environments. This is how it’s done and administered under HPUX for and typically other Unix systems as well if i recall correctly.

I think you’re only option is to either control the LUN assignment (e.g pre-allocate some LUN’s for them to use – once a threshold is hit then hit them up for a storage review). The other way is to investigate performance of the HPUX systems and if it doesn’t adversely affect performance then you could potentially justify a per-port allocation of storage – however you’ll need to keep in mind that if performance requirements increase then you’ll be back where you started from….

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