Not a silly analogy - a very good one. Yechiel Adar Mehish ----- Original Message ----- To: Multiple recipients of list ORACLE-L <[EMAIL PROTECTED]> Sent: Wednesday, October 30, 2002 3:29 AM
> As with any "cached" I/O subsystem technology (i.e. RAID-S, NetApps, etc), > please visualize a water tank. The water tank represents the cache, the > drain from the tank represents I/O throughput rates from the cache to the > hard-drives, and the faucet filling the tank represents the I/O volumes from > the server to the I/O subsystem. The faucet filling the water tank is on a > valve, so that when the tank is full, it does not overflow. Let's say that > the water tank holds 100 gallons (about 400 liters???). The faucet filling > the water tank can vary its rate, anywhere from 1 gal/min to 30 gals/min. > The drain from the water tank operates at 5 gals/min and can not be blocked > or closed. > > Got that pictured in your mind? Now for some scenarios... > > 1) What happens when the faucet is filling the water tank 24x7 at a rate > of 1 gallons/minute? No problem -- the tank never fills, so the flow into > it is never impeded... > > 2) What happens when the faucet is filling the water tank 24x7 at a rate > of 5 gallons/minute? Still no problem -- the tank never fills, so the flow > into it is never impeded... > > 3) What happens when the faucet is filling the water tank 24x7 at a rate > of 6 gallons/minute? Uh oh. In less than two hours, the water tank will > fill, causing the flow of water to be limited to the output rate of 5 > gals/min. Too bad, because we really need to move 360 gallons/hour, or 8640 > gallons/day, through this system... > > 4) What happens when the faucet is filling the water tank for an hour at > 10 gallons/minute for 15 minutes, then at 1 gal/min for the next 45 minutes? > Not a problem -- the capacity of the tank was able to hold the excess input > rate during the first 15 minutes, and whatever accumuated was drained off > before the next "spike" or surge... > > 5) What happens when the faucet tries to run for an hour at 30 gals/min, > then 11 hours at 1 gal/min? Uh oh again. We were only able to run at 30 > gals/min for about 4-5 mins, and then the flow rate got cut back to 5 > gals/min for the rest of the hour. We really wanted 1800 gals to go through > the system during that hour, but it actually took 6 hours to get all 1800 > gallons through; too bad... > > Sorry for the silly analogy, but that's how my brain works... > > ----- Original Message ----- > To: "Multiple recipients of list ORACLE-L" <[EMAIL PROTECTED]> > Sent: Tuesday, October 29, 2002 9:58 AM > > > Russ: > > We're using EMC Clariion disk arrays. These are using EMC's version > of RAID-5; they call it RAID-S. There is 2GB of cache if front of > the disks. They claim that the cache is write guaranteed so that > we'll never lose an update. So far, so good, and the performance > has been acceptable, except (you knew this was coming, huh?) when > we do large file moves from one tray to another, or when doing a > refresh of our SAP stage system. This activity kinda buries the > internal bus as well as the fiber, so that other users suffer. > > I guess to make a short answer even longer, this RAID-S technology > seems to work a lot better than RAID-5 used to. > > Remember, though, YMMV. > > Cheers, > Mike > > -----Original Message----- > Sent: Monday, October 28, 2002 5:24 PM > To: Multiple recipients of list ORACLE-L > > > Hi, > I just got forwarded a whitepaper from Hitachi and Oracle, that compairs > raid 5+ and raid 1 using the TPC-C benchmark test suite. The claim is that > raid 5 is as fast or faster. While I'm waiting for a comparison or raid 5+ > with raid 0+1, I thought I'd take a poll with the list. The benchmark is > using the Hitachi 7700E. > Has anyone heard other recommendations attributed to Oracle that are > pushing raid 5+ as the configuraton for "unrivaled performance"? Has new > disk technology changed the general conception that raid 0 or 0+1 provides > better performance than other raid levels? > > Thanks, > Russ > > -- > Please see the official ORACLE-L FAQ: http://www.orafaq.com > -- > Author: Brooks, Russ > INET: [EMAIL PROTECTED] > > Fat City Network Services -- 858-538-5051 http://www.fatcity.com > San Diego, California -- Mailing list and web hosting services > --------------------------------------------------------------------- > To REMOVE yourself from this mailing list, send an E-Mail message > to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in > the message BODY, include a line containing: UNSUB ORACLE-L > (or the name of mailing list you want to be removed from). You may > also send the HELP command for other information (like subscribing). > -- > Please see the official ORACLE-L FAQ: http://www.orafaq.com > -- > Author: Vergara, Michael (TEM) > INET: [EMAIL PROTECTED] > > Fat City Network Services -- 858-538-5051 http://www.fatcity.com > San Diego, California -- Mailing list and web hosting services > --------------------------------------------------------------------- > To REMOVE yourself from this mailing list, send an E-Mail message > to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in > the message BODY, include a line containing: UNSUB ORACLE-L > (or the name of mailing list you want to be removed from). You may > also send the HELP command for other information (like subscribing). > > -- > Please see the official ORACLE-L FAQ: http://www.orafaq.com > -- > Author: Tim Gorman > INET: [EMAIL PROTECTED] > > Fat City Network Services -- 858-538-5051 http://www.fatcity.com > San Diego, California -- Mailing list and web hosting services > --------------------------------------------------------------------- > To REMOVE yourself from this mailing list, send an E-Mail message > to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in > the message BODY, include a line containing: UNSUB ORACLE-L > (or the name of mailing list you want to be removed from). You may > also send the HELP command for other information (like subscribing). -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Yechiel Adar INET: [EMAIL PROTECTED] Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
