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Dual Processors
How do they work?
carfac




msg:345608
 5:17 pm on Mar 22, 2003 (gmt 0)

Hi:

I am thinking (well, planning) to replace our current server because it is just no longer up to the task. In the course of my shopping, I have seen some servers with "Dual Processors", or at least that have that upgrade path. I am just curious how these work...

Is this essentially haveing two "computers" in one box, one processor doing one, the other doing the other... or do both processors share the same work? If so, how is it split?

Since we are on the subject of upgrades, any suggestions or hot tips for things to look (or look out) for?

Thanks!

Dave

 

txbakers




msg:345609
 6:05 pm on Mar 22, 2003 (gmt 0)

Both your scenarios are correct. They can either split the load or share the load, depending on the load.

The best thing for upgrading, however, is not the processor, but the RAM. Put as much RAM as you can afford into the machine and it will fly.

lorax




msg:345610
 7:23 pm on Mar 22, 2003 (gmt 0)

carfac,
Dual processors are nice but be sure your OS and apps can utilize them. Not all do.

If speed is the issue then the covering the basics will server you better. As txbakers noted, RAM is a good place to start, as is hard drive access time and Bus type - I believe ultra wide SCSI is the fastest out there. Why are these more important? Because servers (especially web servers) spend most of thier time reading and writing data rather than running complex apps that would benefit from the dual processor.

Dual processor explanation can be found here [cadalyst.com].

carfac




msg:345611
 8:13 pm on Mar 22, 2003 (gmt 0)

lorax, txbakers:

Thanks for the responses... and the hints. Without getting into too much detail, I can tell you a bit about my site. Right now, it is on a Celeron 533 with 2 IDE drives (one for OS, one for pages) I use MySQL, and that is supplied by my ISP, though at some point, I would like to get a second box for this, too. The current box now MAXED OUT with 1 Gig of memory, and a 133 bus speed.

I am seeing increased CPU load since I added a forum. This forum and a LOT of my other VH's use a LOT of dynamic paging (built from reads to the MySQL server). What I am considering is a 2.4 gig Intel processor, with a 533 bus, at least 3 SCSI drives (one OS [FreeBSD] and two RAID for the pages). I would again want 1 gig of memory, but hopefully have the future option to add more.

>>>Dual processors are nice but be sure your OS and apps can utilize them.

Can FreeBSD? In this fairly CPU intense environment, would I want to think about this more? (I am starting to see 503 errors...) Also, I would probably start with a single CPU, should I get a box that keeps this option open for the future?

Thanks again!

dave

mechanical messiah




msg:345612
 8:16 pm on Mar 22, 2003 (gmt 0)

another good idea is the new hyperthreading option on intel's processors. on the new fastest processors you can have 2 "virtual" procs in one, since it's got such a high ghz/mhz/however you wanna say it.

lorax




msg:345613
 8:28 pm on Mar 22, 2003 (gmt 0)

carfac,
I encourage you to look into Athlon processors for starters. The Celeron processor is not server grade (it's a cheap alternative to the Intel) and while Intel's are good - Athlon is better IMO. I think FreeBSD will utilize the dual processors - this URL might answer a few questions [davemathews.com] for you.

A dual Athlon with 1GB of RAM, and SCSI drives would be the envy of many webhosts. That's one fast mutha. If you opt for the single cpu - don't bother with buying the dual board as they change so much that in a year or so it's likely the upgrade route will be closed or won't provide a good ROI. It happened to us once or twice.

What RAID level are you thinking of?

carfac




msg:345614
 8:54 pm on Mar 22, 2003 (gmt 0)

lorax:

Thanks! All these XXXalons boggle my mind... How does Xeon compare to Athelon? I suppose you say Athelon.... I will go look that one up! (Xeon had been what I was looking at.) If you do not mind... why do you prefer the Athelon?

I know Celeron is not all that great, but it was our first, and got us online! I will PROBABLY still kepp that puppy online, as a dedicated image server.

Raid level? Probably start with one, but I love the idea of the 0+1. I am most concerned about security of data.... I think even the IDE's we have now are fast enough. If we go to a dedicated MySQL server, THEN I will really think hard about the striping option!

dave

lorax




msg:345615
 9:21 pm on Mar 22, 2003 (gmt 0)

carfac,

>> If you do not mind... why do you prefer the Athelon?

I just think AMD has a better overall design and track record. For years Intel has been the prime supplier of chipsets to the PC market. This forced AMD to think more about what they were building and why in order to survive. Performance wise - the latest Athlon is about the same as the latest Pentium.

sun818




msg:345616
 9:56 pm on Mar 22, 2003 (gmt 0)

AMD is the preferred chipset by many hardware enthusiasts because the price/performance ratio is much better than Intel. Is IDE still an option with the system upgrade? The newest IDE is just as fast, if not faster, than SCSI these days. Either is fine really, but for price/performance IDE is better choice I think. You also need to consider disk contention. Its ideal to place the OS, web server, and mysQL database on separate disks. If you have the budget, go for RAID 0+1 [acnc.com]. If not, RAID 1 [acnc.com], I think is more than adequate. My thought is, for web servers improving the read performance is more important than write performance. RAID 1 doubles your read at the same time securing your data.

carfac




msg:345617
 11:08 pm on Mar 22, 2003 (gmt 0)

Thanks again!

sun818: IDE is of course an option, but i have just heard that SCSI Ultra is soooooooo much faster :) Obviously, the IDE would be less expensive.

Well, I did some looking at the Athlon (which I can now spell correctly!) vs. The Xeon. On Paper the Xeon looks uperiour.... a 533 bus (vs. 400 for Athlon) and twice the size of the L2 Cache (512 vs. 256). Does this translate into performace for a webserver, or is it pretty unimportant?

Hard to beleive my first computer had less memory than the cache on these!

dave

Brett_Tabke




msg:345618
 11:49 pm on Mar 22, 2003 (gmt 0)

I think if you're pages are dynamic and run many programs per page load, a dual processor with about a gig of memory can do more than a scsi drive will.

Anyone know that article on building the 'dream server' from a few months ago? It had comparasions between scsi and ide. It ended up with the die hard scsi guys installing ide. I think it was from a slashdot story.

sun818




msg:345619
 11:51 pm on Mar 22, 2003 (gmt 0)

If you compare UltraATA 100 (IDE) and Ultra2Wide (SCSI), they offer similar performance, but IDE will cost much less for hardware and disk drives. But since I don't know what your ISP specifically offers, I can't say for certain which option is the best performer for you.

carfac




msg:345620
 11:54 pm on Mar 22, 2003 (gmt 0)

>>>ISP specifically offers, I can't say for certain which option is the best performer for you.

My ISP basically just ends at the ethernet connection- I can build whatever server I want!. If IDE are that close- and with the BIG difference in price, I just might go the IDE route!

dave

bcc1234




msg:345621
 12:50 am on Mar 23, 2003 (gmt 0)

It would cost as much to have an IDE raid of type 0+1 or maybe even type 10 (cards that support 10 are usually a bit more expensive) than to use SCSI raid 1. That of course, unless you must use one of those 1U rack mounts.

added:
If you use FreeBSD and need a kick-ass box for a low price, check out vinum. You can use one drive for the OS and 4 IDE drives in a raid volume. That would give you high throughtput and level of redundancy at the cost of just 4 drives.

carfac




msg:345622
 1:49 am on Mar 23, 2003 (gmt 0)

bccc1234:

You know, I looked into vinum... unfortuantely, I am a *nix idiot! I could probably hire a consultant or something to get that working. It is nice that it is right in the OS... but I have also heard an arguement for doing the RAID in hardware (What I was led to believe id that if one drive goes down in vinum, two drives are out (in a 4 drive system) whereas in a hardware system, you can replace the one bad, and the other three will "fix" the fourth...

dave

bcc1234




msg:345623
 2:20 am on Mar 23, 2003 (gmt 0)

It does not matter if it's hardware or software raid. The raid has to rebuild it's stripe

Well, it depends if you are using raid 0+1 or raid 10. Those are different setups and have different properties, but essentially provide the same service.

With 0+1, that's the case. The second drive is not being used if the first in the stripe goes down so all I/O is being done only on the remaining stripe in the mirror.

Good hardware raids are expensive, and the cheap ones are really just software raids. All those $99 cards you see out there do most of the processing in driver software and the hardware part just passes the data to/from the drives.

As I said before, using vinum is the cheapest solution, which would cost you only 4 IDE drives. With $100 a piece, it totals to $400 - good speed, good redundancy.

A good hardware raid that supports raid 10 (and not 0+1) in it's firmware would cost around $400, not inculding the drives.

As far as 10 vs 0+1, that's the only major difference.
With 0+1, if two drives fail on separate stripes - you are screwed. Raid 10, would only die if two drives on the same mirror die.

carfac




msg:345624
 2:29 am on Mar 23, 2003 (gmt 0)

bcc1234:

OK, that makes sense! I guess I had it half-right! Thanks!

dave

carfac




msg:345625
 3:42 am on Mar 23, 2003 (gmt 0)

OK stupid question:

>>>>using vinum is the cheapest solution, which would cost you only 4 IDE drives

From reading the vinium man pages, yes, you do this over 4 drives, 2 stripes, and two mirrors of those stripes... BUT you have to have a FIFTH drive for the OS (as Vinium is NOT bootable).

OK, I am not so smart sometimes, but isn't IDE limited to 4 drives? A primary master and slave, and a secondary master and slave? And what about a CD? Gonna need one of those at some point (although I could just use that to get the OS loaded, and then remove it...)

Dave

lorax




msg:345626
 4:46 am on Mar 23, 2003 (gmt 0)

Whew - look what I missed while I was away! ;)

Re: SCSI versus IDE - the only other reason to consider SCSI over IDE then (since it appears they're about equal in performance) is that SCSI will support more devices. I'm not sure what the limit of the IDE bus is now but I'm thinking you'll need at least a CD and tape/juke/optical for backups.

I believe you indicated that you'll have another box on-line so I assume the two will be networked. You could hang a stand-alone elcheapo box on the network and park a CD and backup unit it that. Or just mirror the drive onto another one.

txbakers




msg:345627
 4:54 am on Mar 23, 2003 (gmt 0)

You could also drop a PCI card with more IDE controllers on it.

lorax




msg:345628
 5:03 am on Mar 23, 2003 (gmt 0)

>> You could also drop a PCI card with more IDE controllers on it.

Sure - go ahead and destroy my elegant solution with something much cheaper! ;)

carfac




msg:345629
 5:50 am on Mar 23, 2003 (gmt 0)

txbakers:

>>> You could also drop a PCI card with more IDE controllers on it....

You can do that? So I could have 8? <show ignorance>I did not know that.</si>

<stupid question> You are sure about that?</sq>

dave

Brett_Tabke




msg:345630
 7:13 am on Mar 23, 2003 (gmt 0)

>more devices

But what's the point? You can only effectively use about 2-5gig in a server environment any way. What could you possibly do with the a 40-200 gig drive or multiple drives?

You don't have the bandwidth, or through put on a single server to warrent that kind of storage. Buying multiple drives for a server is a waste of good cash. The perks are in faster cpu's and bigger pipes.

nosanity




msg:345631
 9:04 am on Mar 23, 2003 (gmt 0)

So I guess building a mirror of tucows downloadable content for your customers to save bandwidth on your behalf would take less than 5 gigabyes? *Grins with satisfaction*

noSanity

bcc1234




msg:345632
 9:50 am on Mar 23, 2003 (gmt 0)

From reading the vinium man pages, yes, you do this over 4 drives, 2 stripes, and two mirrors of those stripes... BUT you have to have a FIFTH drive for the OS (as Vinium is NOT bootable).

Yep, most motherboards come with 2 channels that support 2 drives per channel, but a PCI IDE controller costs almost as little as a PCI NIC. So I don't think it's of any importance.

But what's the point? You can only effectively use about 2-5gig in a server environment any way. What could you possibly do with the a 40-200 gig drive or multiple drives?

True, but if you have raid 1 - you got redundancy. If you have raid 0 - you got throughput on the disk I/O. If you got both of them (10 or 0+1) - you got redundancy and throughput.

So, 4 discs under raid 10 would actually give you a fast and redundtant volume of the size of two disks. It's not a waste, most applications' bottleneck is in I/O.

Besides, not everything out there is made to just serve websites and message boards. I do off-site backups for some of my clients. And space is the only thing I need, since I must keep archives of their documents during incremental backups, but in this case, raid 5 was the most appropriate choice.

Also, think of mail servers, newsgroup servers ... the list goes on...
CSI versus IDE - the only other reason to consider SCSI over IDE then (since it appears they're about equal in performance) is that SCSI will support more devices.

Well, I wouldn't say that's the only reason.
If you use mirroring and striping then yes, but most IDE ans SCSI drives has similar internals, but have different cost. Why? Because SCSI drives are usually made with quality parts and IDEs are the cheap, desktop user choice. IDE drives die more often than SCSI drives, not because of the controller standard, but because of the production quality.

If you got more money than space - then go with SCSI, otherwise, IDE is a good choice.

Brett_Tabke




msg:345633
 10:16 am on Mar 23, 2003 (gmt 0)

I'm more concerned with seek and access time than throughput. Most pages and data coming from disk is well under 100k anyway.

>tucows

Mass file storage not a dynamic environment. If you are doing that, you will need multiple servers anyway for that kind of bandwidth.

>raid

The redundancy factor is mitigated with the newer ultra-reliable drives. If you follow a religious backup procedure nightly or even a couple times a day, I don't see losing too much data. I'd rather have an offsite backup system than spend the money on a raid. I think it all depends on the size of the environment and the frequency of data updating.

Also, not all RAID controllers are equal. Make sure you get the right level for the application (and stay away from proprietary stuff). Some are build for the redundancy factor and some for the access (parallelism) factor.

lorax




msg:345634
 4:11 pm on Mar 23, 2003 (gmt 0)

>>more devices

Brett, I was think more along the lines of supporting devices like CDs and backup solutions.

kwngian




msg:345635
 1:03 pm on Mar 24, 2003 (gmt 0)


Guys (and ladies as well),

SCSI drives will spin to a consistent speed and remains so while an IDE drive will stop and start frequently thus even if an IDE drive is getting closer in terms of speed to SCSI (U160) range, choice for mission critical machines will still be SCSI.

My choice of processor will still be Intel instead of AMD due to overheating problems that are costantly occuring with AMD chips.

Just my personal preference though. Many will disagreed.

Gibble




msg:345636
 3:12 pm on Mar 24, 2003 (gmt 0)

Wow, we have had dual procs in all our servers for a few years now and are buying all our new servers with quad processors. I can't imagine running anything less.

daisho




msg:345637
 3:29 pm on Mar 24, 2003 (gmt 0)

Hello all. Here is my experiances with servers.

1. Dual Processor is very important. Especialy if you are running database and webserver on same box since _EVERY_ visitor will take at least 2 processes (1 for webserver and 1 for database). Now if your traffic is low that it's not a problem. But when traffic grows this will become an issue.

2. I agree with the other comments that RAM is very important. Buy as much as you can. Don't skimp!

3. For servers SCSI is better than IDE. IDE has very impressive speeds but they are single access. Meaning basically one person doing something. IDE does not do Multi-IO very good since it was not made for that. So IDE ends up being better for desktop machines for the price you pay. SCSI handles many many IO operations much more efficiantly than IDE. Servers typicaly have many small operations rather than 1 big operation. In this case you will see a dramatic increase in performance with SCSI in a server environment.

4. I like RAID. I do not do striping since if a drive goes down your array is offline. I do Mirroring. If you get a good controller (I use the Adaptec 5400S) you get faster reads since the controller will use both drives to get data off. But writes are no faster since it needs to write every byte to both drives. The disadvantage to mirroring is that you loose harddrive space. Ie. I have 2 18gig HD's (For OS) and 2 36gig HD's (for webserver) but I only have access to 1 18gig and 1 36gig since the other 2 drives are mirrored and _MUST_ store the same data as the first drive. Stripping gives you security and you don't loose much space but you need to start with 3 drives. 2 data and 1 checksum. So if you loose any 1 drive you can recreate it from the other 2. The nice think is that if you have 4 drives you now have 3 data and 1 checksum so only 1 drive is lost to overhead.

5. I've moved from Intel based to Athlon CPU's. Much more bang for my buck. The advantage of Xeon's is addressable memory. But I beleive you need to buy the higher end XEONS and Motherboards. Last I priced out a Xeon CPU with 2megs cache was about $1000. Then the motherboards were in the range of $2000. The nice advantage is the XEON's can address 16GB - 24GB depending on the Motherboard chipset. Athlon's and other intel CPU max out at 2G Registered ECC or 3G Non-Registered (though in servers Registered ECC is the only way to go).

Dai-Sho

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