Re: asm on san

On Thu, 11 Dec 2008 13:16:01 -0800, joel garry wrote:

> I have to
> admit that it works for my employer, who not only is not doomed but
> keeps me busy with expansion projects. Business needs uber alles and
> all that. The only time it is a problem is when it is operating in
> degraded mode or some rare thing overwhelms the buffering. The more
> usual case is akin to a mostly empty municiple bus, plenty of room for
> quite a bit more riders. I'd like to take the thanks for that, but
> really it's just a reasonable configuration for what it does (ERP/MRP
> OLTP, mostly). If I had to choose between Itanium hp-ux RAID-5 and
> Itanium Windows RAID-10, I wouldn't pick the Windows.

Joel, I used to share your bias against the Windows boxes but Windows Server 2008 is actually an excellent OS, with a great shell. It definitely has a potential. I am not sure whether there is a version of "vi", native perl installation and some utilities like grep, awk and find, but the OS holds a promise. It can definitely give Unix a run for its money.

As for RAID 1+0 vs RAID 5 debate, RAID 5 can perform well when equipped with the copious amounts of NVRAM but that makes it expensive. Unfortunately, if I give consent to RAID 5, I will probably get a cheapo version with 2GB of NVRAM and an explanation from the CIO that the sales person told him that he doesn't need more than that. Low level RAID 1+0 will always beat low level RAID 5, at least in my experience. If you have enough money for the premium HW, then it doesn't really matter. The small difference in price will be decided by the current ratio in memory prices vs. disk prices. You and me both know that RAID 5 must distribute things over 5 disks, using a complex and compute intensive algorithm. The block is not written until it's distributed across all 5 disks. That means that write can only as fast as the slowest of the 5 disks. Granted, ample memory configuration will alleviate the pain but I am unwilling to rely on that in case of multi TB databases where a sudden query from Crystal Reports or Business Objects can attempt to summarize an enormous table and flush your cache. My experience tells me that RAID 5 usually means trouble.

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