Does anyone use serial ATA drives in there servers? How do they compare to SCSI?

Wondering the same, I am trying to install one over redhat 9 but it will not recognize the drive even though the it's listed in the bios fine. It registers as a SCSI drive which makes it even stranger.

Anyone install one of these over Linux distro?

 

ATA drives do indeed show as SCSI drives.

As such shown in dmesg

scsi1 : ata_piix
Using anticipatory io scheduler
Vendor: ATA Model: ST3120026AS Rev: 3.18
Type: Direct-Access ANSI SCSI revision: 05
SCSI device sda: 234441648 512-byte hdwr sectors (120034 MB)
SCSI device sda: drive cache: write back
sda: sda1 sda2 sda3 sda4 < sda5 sda6 sda7 sda8 >
Attached scsi disk sda at scsi0, channel 0, id 0, lun 0
Vendor: ATA Model: ST3120026AS Rev: 3.18
Type: Direct-Access ANSI SCSI revision: 05
SCSI device sdb: 234441648 512-byte hdwr sectors (120034 MB)
SCSI device sdb: drive cache: write back
sdb: sdb1

 

Apparently SATA drives are almost as fast as SCSI drives. But cheaper and bigger! I have two SATA drives in one server and a SATA drive in an office PC. No complaints about either machine.

 

That's great, I have two server I set up today with them and centos. So far they both pass testing with no errors. I love when technology comes together easily. :D I need to go donate some money for centos what a clean OS.

 

Sorry, but for small reads and writes, which is generally what a web server will do, you will see much better performance with SCSI drives. The only SATA that will come close are the 10K RPM WD Raptors as they have command queuing.

 

Quite a few hardware gurus over at WHT would beg to differ.

 

SATA vs SCSI

I could see this going on for ever as a debate - as there will be fans on both side of the issue.

SATA has come far - and will, in my opinion, continue to the point where SCSI will no longer be an option - at least the SCSI we know today.

SCSI is all around Expensive - but in some instances there are justifications for higher performance - Likewise there are justifications for less expensive disks as well.

The main difference between the drives SATA vs SCSI are as follows:

SATA - this is a serial implementation of ATA. SATA drives generally use a single processor for both the execution of command and handling the interface - as well as controlling the head position through servos. it is for this reason that ATA drives have such factors as rotational vibration (wear) and more processor time needs to be dedicated which can affect the performance of the drive.

This is the reason you usually will see lower RPM for the ATA drives (SATA or IDE) - it is also the reason these drives generally carry a 1 year warranty - if any at all.

SCSI drives all use the same bus - and in certain circumstances this constellation can lead to bottlenecks in peak data traffic. SCSI Drives however use a processor for execution of commands and handling the interface, but also generally use a second processor to control the head positioning through the servos.


Today - Depending upon your needs - the SATA drives may be the answer your looking for.

Tomorrow - I believe that SATA will take a prominent place in the hard drive market while SCSI drives move towards SAS (Serial Attached SCSI)

SAS is the best of both worlds- it is promised that the first generation of these will provide full duplex performance @ 3Gb/sec, while future generations will provide up to 6 Gb/sec throughput.


While many thought that SATA was the new era in storage scalability, SAS which is basically a SATA implementation of SCSI clears away the limitations that SATA has in terms of scalability.


SAS will provide devices reading up @ 3.6msec seek times with 15K RPM with the MTBF running @ 1,200,000 enterprise workload hours (24x7) while SATA in its 7200K RPM 9.5msec read times provides for only 600,000 hours running 8 hrs/day 5 days a week.


Interestingly enough with the implementation of SAS - users can use both SAS and SATA drives interchangeably - provided they have the right hardware. SAS will allow for up to 128 devices per expander ! Theoretically that allows for a fan which could have up to 16,000 devices per SAS domain...


While SAS is being built to withstand the performance requirements of enterprise use - SATA is still marketed towards the less demanding - cost conscious desktop environment... but some of us web hosting guys use it.

In closing - SCSI is a dying breed- there will be some that will always use SCSI - like there are some that will always use Windows -

There are some that will use IDE - for the same reason.

Cost is always a factor - but so is speed - the best of both worlds today is SATA.

Kind Regards,

Glenn Kelley


---
Glenn Kelley, President of VineHosting (www.vinehosting.com) , a non-profit web hosting firm providing low cost and free hosting for Christian Ministry writes for various industry magazines - and would love your feedback.

 

SATA not recognized by Linux

In most newer distro's SATA will be recognized by Linux.

i do know many of the SATA controllers are difficult to run with Fedora 1, 2, (some even with 3) however CentOS does SATA very well.

CentOS is basically Red Hat Enterprise minus the bloat of the Red Hat being everywhere you turn...

CentOs will run Cpanel just fine as well.

visit www.centos.org for additional details on where to obtain and such...


Red Hat Enterprise 3 - provides excellent support for SATA as well.