Re: Quarterly RAID5 Rant - enhanced

Basically, what Art says is that using raid5 rather than raid10 is a means of saving money on protection of your data. Can you afford to do this? But if you are using Microsoft products are can you really be concerned about protecting your data? I have never known the idea of protected data and Microsoft to be happy bedfellows. But on a more serious note:- How many customers are really aware of this problem. How many are using Raid and what types? Perhaps if we got those answers we could establish whether the industry in general is still prepared to take risks with their data to save a few pennies. regards Malcolm ----- Original Message ----- From: "Andy Kent" <andykent.bristol@virgin.net> To: <informix-list@iiug.org> Sent: Thursday, November 27, 2003 9:00 AM Subject: Re: Quarterly RAID5 Rant - enhanced > Interesting and comprehensive discussion. > > But I couldn't help noticing that in the Microsoft Guide To Get SQL > Server Certification" (and let's resist any parochial pettiness in > this debate) there were some sample questions on "Which RAID level > would you choose in the following scenarios" and one of the answers > was RAID 5. > > Although I shuddered at the answer myself, (and would probably have > put something else and therefore lost a mark), and whatever we might > say about Microsoft or SQL Server, it's interesting to note that an > organisation with the wellie of Microsoft is still recommending RAID 5 > to its up-and-coming DBAs. > > Also I was in the fortunate position to be able to try configuring IDS > 9.3 on a big Sun with twin T3 arrays last year, tried RAID5 on one and > RAID10 on the other and was surprised to find that both read and write > performance were almost identical. > > Now you know I'm with you on your disdain for RAID5 Art but I'd be > interested to hear your (or anyone else's) feedback on all of this. As > I said it would be nice if we could keep the parochial stuff out of > the debate. > > Andy sending to informix-list

"malcolm.iiug" wrote: > > Basically, what Art says is that using raid5 rather than raid10 is a means > of saving money on protection of your data. Can you afford to do this? > > But if you are using Microsoft products are can you really be concerned > about protecting your data? I have never known the idea of protected data > and Microsoft to be happy bedfellows. > > But on a more serious note:- > How many customers are really aware of this problem. How many are using > Raid and what types? Perhaps if we got those answers we could establish > whether the industry in general is still prepared to take risks with their > data to save a few pennies. Here, the answer is definitely yes. And SAN (re-)sellers do play their part in that game: [ all of the following disks are 10k rpm, 8MB ondisk cache] 1 GB is 1.00 Euro on Serial ATA 1 or par. ATA133 1 GB is 3.20 Euro on a stand alone SCSI disk (with SCSI320) interface Inside a SAN the very same SCSI disk is priced at 15 Euro / 1 GB. No wonder, why one has to look after the cheapest way to go on the winding road of storage consolidation. Industry seems to be able to cope with the loss of performance easier than with the 15 fold increase of $$ (compared to IDE) What I cannot understand is, that noone seems to see the fact that you get the same number of GB for the same price, but almost 2 times the sustained access rates (no of seeks/sec that is) if you go with IDE 250 GB and use only 25 GB of each disk. The 'outer', faster tracks ..... In terms of 2KB pages per I/O: (both solutions via 2 FC 2Gbit/sec attachments) 32 IDE serial ATA 1 disks with 2 IDE RAID controllers, 8+8 disks on eachcontroller, all disks 250 GB, but only 146 GB used per disk: Performance: approx 210000 pages dskrd / sec 8 disks in a SAN (2 times 3+1 in 2 RAID5 cages) inkluding 4GB SAN cache all disks 146 GB Performance: approx 121000 pages dskrd/ sec (Performance as seen on onstat -p, so on the SAN it includes all in-SAN caching, which doesn't help too much) (the SAN is still 10% more $$, but there is no IDE solution with higher price on the market) dic_k -- Richard Kofler SOLID STATE EDV Dienstleistungen GmbH Vienna/Austria/Europe