OK but I was assuming that mirroring would stay so that means either RAID 5 or RAID 10 thus at least one extra drive. Of course each extra drive results in the better performance.

I'm still curious though; given the same number of drives, what method would yield the better read performance, RAID 5 or RAID 10?

RAID 0 is probably the fastest. For the db I don't want to deal with parity checking, so a RAID 0+1 (10) works well for perf. The thinking now is four drives raid 10, and two drives raid 1 (for the OS).

I think that these SPEC's are way over the top here:

The two systems we are getting quotes for (some preliminary prices bring it to about $7.5k each):

* Dual Processor Quad Core 3.0 Ghz 12MB L2 Cache
* 32 GB RAM 800 Mhz
* SAS RAID Controller
* Seven Hard Drives at 15K rotation (most likely Seagates)
o Two in RAID 1
o Four in RAID 10
o One cold spare
* 1600 Mhz system bus speed

I think that two of the DRIVES should be SATA SSD's and you don't need 15,000 RPM discs to do the work when the latest ones 7200.11's from Seagate at 7200 RPM have sufficient speed to deliver data quickly.

And the SATA SSD's don't have to be all that large either.
The sweet spot on SATA SSD's for right now as I see it is the ones around 64 GB capacity;

Here's a couple of links to see the examples.


http://www.newegg.com/Product/Productcompare.aspx?Submit=ENE&N=2013240636%201421530856&bop=And&CompareItemList=N82E16820609234%2CN82E16820609243%2CN82E16820183090%2CN82E16820609262%2CN82E16820609242%2CN82E16820609241

http://www.newegg.com/Product/Productcompare.aspx?Submit=ENE&N=2013240636%201421530856&bop=And&CompareItemList=N82E16820609243%2CN82E16820227279%2CN82E16820183090%2CN82E16820609234%2CN82E16820609244

You would want them in the 4.0 inch form factor cartridge so they go in the drive bay easily.

2 x RPM = 1/2 avg access time thus results in dramatic performance improvement when performance is predicated largely on disk access time.

Regarding SSD size, I believe the complete DB would have to fit unless frequently accessed DB records can be placed in a swap file. Dunno that MySQL supports that. Until Paul knows how large a DB can be expected, the number x size x price can't be determined.

well, there are advantages and disadvantages to SSDs now, as I have done a lot more reading on them - first of all, UltraSCSI and SATA 300 (and presumably those SAS configuration in those servers) will still out perform the current SSDs, as they have a very very low read speed, and even lower write speeds - plus, their current access times are barely scratching those of HDs, and random write times are still way above platter based drives.

The only real option is to go for DRAM based SSDs - and those are prohibitively expensive for now.

The 15K rpm drives are going to be the best for setting up a server in the next 6 months - after that, who knows what the drive manufacturers will release?

A problem of the past is the MTBF - most SSDs are around 1 Million, with a few being 2 and a relative few being as high as 4 - whereas SCSI / FC usually have averages of 1.5M and SATA around 1M also. However, access times, read times, and write times, specially random writes, are a big factor in the slow move to SSDs. Well, those and the prohibitive cost for low volumes of space.

SSDs are a great idea, but when Longhorn stepped down from requiring Hybrid drives in notebooks, development slowed on them dramatically. Which, as remains to be seen, may be beneficial for the end user in the long run - it has allowed the manufacturers to take a step back and pour more money into R&D - which will, presumably, lead to better, faster, and more fault tolerant drives.

Some good reading:

http://storageadvisors.adaptec.com/2005/12/16/can-sata-breach-the-chasm/

http://searchstorage.techtarget.com/news/column/0,294698,sid5_gci1121675,00.html

I sure didn't see anything in the Benchmark Reviews that would make me want to jump on the SSD bandwagon - except maybe for road warriors and their notebooks - where weight, battery life, heat, and noise (or lack of it during presentations), and the ability to take physical abuse (drops) is important. There was nothing in their conclusion that suggests they are ready to recommend SSD either.

Yes, one day, there will be no moving parts in all our hard drives, but not today.

For the money - for the most bang for the buck, I recommend more RAM and bigger/more drives.

15K RPM HDs are real screamers (literally and figuratively) - they are fast, but boy do they make a racket, and they typically generate more heat too.

_________________
Bill (AFE7Ret)
Freedom is NOT Free!

I just went back to the Seagate SATA 7200.11 because of two WD Raptors that make too much heat and too much noise;
and were two unstable cans of worms.

And as soon as the SSD's come down in price as all new technology does;
Then all HDD's in my house are going to become relics from the past and sold to the highest bidder.

SSDs will have to come down in price, but go way up in capacities before they supplant the hard disk drive.

_________________
Bill (AFE7Ret)
Freedom is NOT Free!

I was basing my analysis of access times based upon the data supplied in those drives that Pan Irish supplied in the links, and noting the the fastest access times were 9ms - I have seen SATA drives with faster access times than that.

Now, DRAM based SSDs I'll grant probably have much faster access times - but I had not read any real stats on a side by side comparison yet. I had seen values ranging from 9ms to 23 ms for *access* times - not very good at all.

My IDE 7200 rpm drives all have sub 13ms access times, so I am still not seeing the major advantage in SSDs yet.

Not saying you are wrong, Bill, because what you wrote is what I was supposing at first myself - after all, it's memory, there is no HD to spin up, etc. - but reading *actual* stats of drives already out on the market has led me to rethink my initial belief.

From the Tweaktown review:

_________________
Bill (AFE7Ret)
Freedom is NOT Free!

There are a lot of advantages.
Like being able to use it through the front of the tower where I used to install the floppy and being able to pull the SSD out and put it in my pocket.
Look on the crucial site about the kit for installation of SSD's in various ways.

And the manufacturers are GOING to have a "PRICE WAR" on this one,
There is a lot of memory out there and they cannot afford to shut down a production facility to dry up the market as they all want to have product available to ship.

I can foresee desktop applications that make use of SSD technology in a big way. However in this topic we're discussing how CC servers could best be upgraded. Maybe I'm missing something but it seems that SSDs don't quite measure up just yet.