As a slightly seasonal touch of lightness I though I’d just do a comparison of DAS and SAN storage
|
Item |
DAS |
SAN |
|
Basic Storage Cost |
Good |
Hideously expensive |
|
Ease of Use |
Simple |
How many storage engineers and system administrators does it take to change a lun ? |
|
Performance Monitoring |
Easy |
Almost Impossible |
|
Ability to modify configuration |
Easy |
Most “ automatic/dynamic “ so largely not. |
|
Actual Performance |
Predictable |
Who knows |
|
Expandability |
Pretty simple |
Expensive e.g. how much for a tray of disks ???????? |
|
Redundancy |
Dual controller cards, dual cabling, multiple power supplies, hot spare disks – pretty good. |
Allegedly very good. |
At a recent user group meeting I posed the question about DAS vs SAN performance and were DBAs generally very satisfied with SAN storage. The overall impression I got was that generally us DBAs don’t feel we get value from the tin and that the storage guys are not very keen to talk to us.
A disk is a disk is a disk so I’m often slightly perplexed that when I test I get such differing results, it’s pretty obvious to me that there is contention on most sans, and here I mean the whole Storage Area Network not just the actual storage.
I’m still waiting for a rational explanation as to why a handful of internal SAS disks can consistently outperform a couple of very expensive SANs over a wide range of different tests including application code.
( The exception here being ioMeter which it seems you can configure to prove one set of storage runs faster than another when tested with ioMeter when every other test proves ( ? ) otherwise – I’m still attempting to get my head around this one )
As ultimately the systems I tend to support all have a requirement for performance I find it increasingly difficult to justify the use of a SAN with SQL Server.
As a byline I’ve just replaced the hard drive in one of my laptops with a SSD , http://www.offtek.co.uk/item_detail.php?id=575331&maincat=1&subcat=99
It’s not the fastest SSD in the world but it does appear to make the whole laptop so much quicker, certainly startup of XP is pretty quick, as laptop disks are so slow this is quite a good way to breathe new life into your laptop.
I’m still thinking about SSD for my server !!