On Wed, Oct 1, 2008 at 11:53 AM, Ahmed Kamal < [EMAIL PROTECTED]> wrote:
> Thanks for all the opinions everyone, my current impression is: > - I do need as much RAM as I can afford (16GB look good enough for me) > Depends on both the workload, and the amount of storage behind it. From your descriptions though, I think you'll be ok. > - SAS disks offers better iops & better MTBF than SATA. But Sata offers > enough performance for me (to saturate a gig link), and its MTBF is around > 100 years, which is I guess good enough for me too. If I wrap 5 or 6 SATA > disks in a raidz2 that should give me "enough" protection and performance. > It seems I will go with sata then for now. I hope for all practical purposes > the raidz2 array of say 6 sata drives are "very well protected" for say the > next 10 years! (If not please tell me) > ***If you have a sequential workload. It's not a blanket "SATA is fast enough". > - This will mainly be used for NFS sharing. Everyone is saying it will have > "bad" performance. My question is, how "bad" is bad ? Is it worse than a > plain Linux server sharing NFS over 4 sata disks, using a crappy 3ware raid > card with caching disabled ? coz that's what I currently have. Is it say > worse that a Linux box sharing over soft raid ? > Whoever is saying that is being dishonest. NFS is plenty fast for most workloads. There are very, VERY few workloads in the enterprise that are I/O bound, they are almost all IOPS bound. > - If I will be using 6 sata disks in raidz2, I understand to improve > performance I can add a 15k SAS drive as a Zil device, is this correct ? Is > the zil device per pool. Do I loose any flexibility by using it ? Does it > become a SPOF say ? Typically how much percentage improvement should I > expect to get from such a zil device ? > ZIL's come with their own fun. Isn't there still the issue of losing the entire pool if you lose the ZIL? And you can't get it back without extensive, ugly work?
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