Why not SCSI?

[RebateMonger]

Originally posted by: L00ker
...AFR's (Annual Failure Rate) on a SCSI 15k drive are ~.65% SATA drives are ~.75%...

I talked to an fellow who develops disk-based backup arrays, and who also worked in the hard drive industry for years. He says that they used to use SCSI drives in the arrays and have now gone to SATA. He claimed that their array failure rates have been the same with SATA and SCSI.

 

[d3n]

Originally posted by: RebateMonger

Originally posted by: L00ker
...AFR's (Annual Failure Rate) on a SCSI 15k drive are ~.65% SATA drives are ~.75%...

I talked to an fellow who develops disk-based backup arrays, and who also worked in the hard drive industry for years. He says that they used to use SCSI drives in the arrays and have now gone to SATA. He claimed that their array failure rates have been the same with SATA and SCSI.

I can see this. Also new RAID methods are decreasing the liability inherint in SATA disks. With raid 10 and raid 6 being preferable.

 

[piasabird]

I think it is all about uptime for the server market. All the spares in the world are not any good if your server goes down more often, you can loose money if your business depends on your server.

 

[L00ker]

Originally posted by: d3n

Originally posted by: RebateMonger

[I talked to an fellow who develops disk-based backup arrays, and who also worked in the hard drive industry for years. He says that they used to use SCSI drives in the arrays and have now gone to SATA. He claimed that their array failure rates have been the same with SATA and SCSI.

I can see this. Also new RAID methods are decreasing the liability inherint in SATA disks. With raid 10 and raid 6 being preferable.

Yeah we sell our arrays as raid 10 and raid 50, and the option (hidden) to use raid 5 but we advise cusomers to NOT use raid 5 because of the risk of failure and the performance goes down as well. In practice the SATA drives stand up pretty well although I just bought a SATA II 250gb WD RE(Raid Edition which is supposed to be the more reliable) variety from ZZF and it already crapped out on me which pisses me off to no end as it was in my new build for less than a week! I should have just grabbed one from work since we do use WD drives in our arrays... but they are 'special' wd drives . How is ZZF about returns???

 

[fire400]

get refurb drives with a U320 controller, ownage for under 300 USD

 

[imported_RedStar]

this thread got me into looking at the raptor as an O/S disk

here is an extensive but old (2003) review comparing the raptor (36 gig at the time) to SCSI.

http://www.xbitlabs.com/articles/storage/display/wd-raptor.html

lack of command queing really hurt it.

so here is a 2004 follow up with a raptor 2 using sata 2 technology with the right controller that supports command queing

http://www.xbitlabs.com/articles/storage/display/wd-raptor2.html

--

 

[Googer]

Originally posted by: Fullmetal Chocobo
At this point, you'd be better off at looking for SAS hardware.

SAS controllers cost $500+, the opening post is referring to the low cost of obsolete Ultra 160 SCSI. He also needs to keep in mind that U160 drives are not very fast and that newer Ultra 320 drives are reverse compatable with Ultra 160 HBA's (Host Bus Adapters).




The SCSI Parts Kings-
http://granitedigital.com/catalog/indx_scsi.htm

 

[bwatson283]

The new SATA drives like 120gb and up are alot cheaper and last longer. The shelf life of a SCSI is half the time as a SATA! SATA comes in 10k rpm already, i think 15k rpm are out also. all in all, SATA is 10 times better.

 

[Googer]

Originally posted by: bwatson283
The new SATA drives like 120gb and up are alot cheaper and last longer. The shelf life of a SCSI is half the time as a SATA! SATA comes in 10k rpm already, i think 15k rpm are out also. all in all, SATA is 10 times better.

Thats a mouthload of Bullsh*t. SCSI and all other enterprise class drives are rated for a minimum of one million hours MTBF (most are higher than that) most desktop drives are rated for at least half that (500,000 hrs MTBF).

 

[L00ker]

Originally posted by: bwatson283
The new SATA drives like 120gb and up are alot cheaper and last longer. The shelf life of a SCSI is half the time as a SATA! SATA comes in 10k rpm already, i think 15k rpm are out also. all in all, SATA is 10 times better.

Define your idea of better? Lower cost for performance? Maybe but SCSI isn't JUST about performance SCSI's main benefit is reliability, SATA although promising has not stood the test of time, I mean really think about it it has already been replaced in what 5 years with SAS? and Do you understand what SAS is? basically SCSI over a SATA bus....

 

[Twinpeaksr]

I have run SCSI for years, and as has been hinted at it is the reliability. SCSI not only has a better MTBF, more reliable motor design, and better ability to run many devices on a single bus, it has error correcting, something that ATA drives have not and still do not have. Error correction on ATA drives is completed by the OS, the SCSI architechture takes care of this itself. This is why it is used more for servers because, as was identified earlier, uptime in everything, and even though you can get 3 SATA drives for the price of 1 SCSI, if you need to bring that server down to do repairs, it costs a lot of money.

The speed numbers are also hard to comprehend. Ever computer is different, different software, different drive fragmentation, different users with different use patterns. Some of these apps SCSI will prevail, some SATA will, and the vast majority will not produce a noticable difference. I had a professor once tell me "There are lies, there are damn lies, and then there are statistics. We can run a test that shows SCSI is faster, we can run one that shows SATA is faster, but they don't mean jack unless your main application is a benchmark test.

Believe what you want to believe and use what works best for you. Most people are better off using SATA, it is fast and cheap. SCSI was never intended to be used in the desktop market, the price illustrates that. but for those that demand high reliability, stability, and several devices on a bus, SCSI is the answer.

PS - Firewire is actually based on the SCSI protocal as well, it has the error correction built in. Too bad we can't get more support for that as it would provide a more reliable alternative to SATA and the price trade off would be minimal.

 

[eastvillager]

SCSI does jack all on a desktop. I don't care how much you think you're doing, you're not. The only real advantage you can get is 15k RPM(vs. 10k RPM), which will probably be offset by drive electronics tweaked for server access patterns, not desktop access patterns. That tweaking of electronics for access patterns can make a very large difference, which is one of the reason newer 7200RPM drives were beating the 10k 36GB and original 74GB raptors on some benchmarks.

Somebody keeps spouting something about multiple threads. That is particularly funny, since a drive has no idea what a thread is, much less direct interaction with them. All of that is handled on the OS side in IO buffers. You can have drives and controllers that look deeper into the queue and reorder the requests to minimize head travel, etc., but again that is only going to buy you something in a heavy multi-user environment. Even running a bunch of programs at once as a single user, you're typically doing a big load to get the program into memory and after that you do tiny reads/writes for data, which is no big deal.

In the enterprise space, SCSI drives generally have the highest MTBF. That is very important, especially in an environment with a high number of spindles. I've got customers who even with that high MTBF are replacing 1-3 spindle PER DAY. Additionally, SATA, at least initially handled drive errors/disconnects in a way that made the drives particularly unsuitable for any type of RAID useage. The big enterprise vendors have worked at fixing this in their SATA offerings.

The main reason I wouldn't put SCSI into a desktop is the cost of a controller that is actually worth buying. I don't want to hear 'ebay', ebay doesn't cut it when I'm spending that kind of money. I'm not going to buy a ferrari from joe bob's used auto sales and I'm not going to buy enterprise hardware on ebay. Call me crazy. Anyways, back to my point. The money for a good controller can be invested elsewhere, yielding a much better return on investment(in terms of overall system performance). I can build a stripe of 3+ 10K RPM SATA drives for what it costs to buy a controller and 1 15K RPM drive.

 

[jose]

Originally posted by: bwatson283
The new SATA drives like 120gb and up are alot cheaper and last longer. The shelf life of a SCSI is half the time as a SATA! SATA comes in 10k rpm already, i think 15k rpm are out also. all in all, SATA is 10 times better.

This is totally, stupid....

I have 18yr old scsi drives still running fine. We just had to pull them be cause of size.. ie. 2gig Barracuda's..

In the real world, scsi is king for performance..

Now I'm not saying there is no room for sata.

We use 15k scsi for application servers and 7200rpm sata's for mass storage.. all on LSI scsi/sata hardware controllers.


BTW, I have different types in my personel workstation.

2 - 15K scsi drives for OS & applications.
1 - 10k4 scsi drive for backups
and 1 - 10k 150g raptor for work/scratch/temp type work.

There is a noticable difference in 15k & 10k access times.
2 of my systems use 15k drives while my other 2 systems use 10k drives.

When I work on my customers 7200rpm drive systems it takes what seems forever to get things done.. they are ok but you can feel the difference in system responsiveness..

Regards,
Jose

 

[L00ker]

Originally posted by: eastvillager
Somebody keeps spouting something about multiple threads. That is particularly funny, since a drive has no idea what a thread is, much less direct interaction with them. All of that is handled on the OS side in IO buffers. You can have drives and controllers that look deeper into the queue and reorder the requests to minimize head travel, etc., but again that is only going to buy you something in a heavy multi-user environment. Even running a bunch of programs at once as a single user, you're typically doing a big load to get the program into memory and after that you do tiny reads/writes for data, which is no big deal.

Wrong it's not the OS threads the SCSI multi-threading spec refers to it is drive access unlike IDE each drive is independant and does not need to ask the controller for bus time, IDE devices need to be given 'time' on the bus hence the names Master/Slave. SCSI Will allow multiple devices to perform functions simultaneously on the bus this is why it's referred to as 'multi-threading' if you would like some whiepapers that illustrate this I woulc be more than willing to point them out...

Originally posted by: eastvillager
The main reason I wouldn't put SCSI into a desktop is the cost of a controller that is actually worth buying. I don't want to hear 'ebay', ebay doesn't cut it when I'm spending that kind of money. I'm not going to buy a ferrari from joe bob's used auto sales and I'm not going to buy enterprise hardware on ebay. Call me crazy. Anyways, back to my point. The money for a good controller can be invested elsewhere, yielding a much better return on investment(in terms of overall system performance). I can build a stripe of 3+ 10K RPM SATA drives for what it costs to buy a controller and 1 15K RPM drive.

So an adaptec ultra320 (39320A-R for instance) Is not suitable because it came from ebay? That to me sounds like some pretty rediculous logic and personally a 39320 should be suitable for a LOT of users. So please explain why the equipment sold on ebay is not going to 'cut it' since there are quite a few vendors that sell new stuff there at wholesale prices as well? Thats like saying your not going to buy cd's at walmart because they MUST be a lower quality than what you buy at tower records after all it IS wal-mart.... just plain dumb IMO

 

[Googer]

Originally posted by: jose

Originally posted by: bwatson283
The new SATA drives like 120gb and up are alot cheaper and last longer. The shelf life of a SCSI is half the time as a SATA! SATA comes in 10k rpm already, i think 15k rpm are out also. all in all, SATA is 10 times better.

This is totally, stupid....

I have 18yr old scsi drives still running fine. We just had to pull them be cause of size.. ie. 2gig Barracuda's..

In the real world, scsi is king for performance..

Now I'm not saying there is no room for sata.

We use 15k scsi for application servers and 7200rpm sata's for mass storage.. all on LSI scsi/sata hardware controllers.


BTW, I have different types in my personel workstation.

2 - 15K scsi drives for OS & applications.
1 - 10k4 scsi drive for backups
and 1 - 10k 150g raptor for work/scratch/temp type work.

There is a noticable difference in 15k & 10k access times.
2 of my systems use 15k drives while my other 2 systems use 10k drives.

When I work on my customers 7200rpm drive systems it takes what seems forever to get things done.. they are ok but you can feel the difference in system responsiveness..

Regards,
Jose

:thumbsup:

 

[Googer]

Originally posted by: L00ker

Originally posted by: eastvillager
Somebody keeps spouting something about multiple threads. That is particularly funny, since a drive has no idea what a thread is, much less direct interaction with them. All of that is handled on the OS side in IO buffers. You can have drives and controllers that look deeper into the queue and reorder the requests to minimize head travel, etc., but again that is only going to buy you something in a heavy multi-user environment. Even running a bunch of programs at once as a single user, you're typically doing a big load to get the program into memory and after that you do tiny reads/writes for data, which is no big deal.

Wrong it's not the OS threads the SCSI multi-threading spec refers to it is drive access unlike IDE each drive is independant and does not need to ask the controller for bus time, IDE devices need to be given 'time' on the bus hence the names Master/Slave. SCSI Will allow multiple devices to perform functions simultaneously on the bus this is why it's referred to as 'multi-threading' if you would like some whiepapers that illustrate this I woulc be more than willing to point them out...

Originally posted by: eastvillager
The main reason I wouldn't put SCSI into a desktop is the cost of a controller that is actually worth buying. I don't want to hear 'ebay', ebay doesn't cut it when I'm spending that kind of money. I'm not going to buy a ferrari from joe bob's used auto sales and I'm not going to buy enterprise hardware on ebay. Call me crazy. Anyways, back to my point. The money for a good controller can be invested elsewhere, yielding a much better return on investment(in terms of overall system performance). I can build a stripe of 3+ 10K RPM SATA drives for what it costs to buy a controller and 1 15K RPM drive.

So an adaptec ultra320 (39320A-R for instance) Is not suitable because it came from ebay? That to me sounds like some pretty rediculous logic and personally a 39320 should be suitable for a LOT of users. So please explain why the equipment sold on ebay is not going to 'cut it' since there are quite a few vendors that sell new stuff there at wholesale prices as well? Thats like saying your not going to buy cd's at walmart because they MUST be a lower quality than what you buy at tower records after all it IS wal-mart.... just plain dumb IMO

Actually CD's you buy at walmart (and kmart) are often censored and certain tracks are sometimes altered or omited.

And that is a fact....


EDIT: It should also be known that LSI Logic HBA's are cheaper than ADAPTEC's and quite often out perform ADAPTEC HBAs. Another thing about LSI is that their Drivers are known for their legendary reliablity, quality, performance, broad platform support, and STABILITY!

http://www.lsilogic.com/index_flash.html

 

[L00ker]

I am well aware that LSI is a very good manufacturer however the point is adaptec is just as well (if not better) known for it's SCSI offerings, qlogic also makes great cards, I work in the iSCSI buisness so I am still waiting for LSI to produce a great iSCSI HBA as the qlogics could be better.

 

[sechs]

Originally posted by: cleverhandle
So many people in this thread trying desperately to justify the money they sunk into a 15K SCSI setup.

You should see the threads where people are desparately trying to justify the money that they sunk into a Raptor or a RAID array.

The fact of the matter is, if you're trying to get good bang for the buck on desktop, SCSI, Raptors, and RAID are not where it is at. Even power users can get good performance from pedestrian 7200RPM ATA drives, used individually. If you have money to burn and want the best, however, you're going to invest in a SCSI (or SAS) setup.