So, in the past I have been very anti-hardware raid, mostly because the cards I could afford wanted to charge me what another 3 spindles would cost, and usually had only 64MiB of battery-backed cache. Last time I benchmarked one of those cards, they were largely indistinguishable, performance wise and reliability wise from linux md (at the time I was testing the 'half failed' mode that so many consumer sata drives fall into. Both the hardware raid I tested (an expensive 3ware) and md dealt poorly with the half-failed drive. I solved the problem by simply moving to 'enterprise' sata, and settled on linux MD and raid 1+0, because I saw no benefit to paying for the raid card.)
Anyhow, I'm hearing things about new servers from dell and HP coming with RAID cards that have on the order of 1GiB of cache; and better, it's flash-based cache, so no battery modules to pay for/worry about. With that kind of cache, it seems to me like it may be time to re-evaluate my prejudices; with enough persistent write cache, raid5 can actually give better performance, from what I understand, than the raid 1+0 I use, given the same number of spindles, but that cache is pretty important. Anyhow, I was wondering what experiences others have had with this? I mean, I'll have to start building larger boxes, I imagine, to justify the cost of the card (my current systems are 8 core, 32GiB ram 4 disk systems; it probably makes sense for me to double or triple that, which is pretty easily doable.) What I'm wondering, though, is what success other people have had with these cards, and with what Linux kernels? -- Luke S. Crawford http://prgmr.com/xen/ - Hosting for the technically adept http://nostarch.com/xen.htm - We don't assume you are stupid. _______________________________________________ Tech mailing list [email protected] https://lists.lopsa.org/cgi-bin/mailman/listinfo/tech This list provided by the League of Professional System Administrators http://lopsa.org/
