We help IT Professionals succeed at work.

centos - find out how fast your sata ports are.

allwebnow
allwebnow asked
on
Is there a command or a way to find out how fast your serial ports are on a server.  I need to know whether I need to upgrade to a 3gbps sata card vs. the onboard i'm using now which I think (but don't know) is a 1.5gbps.  The server is a core2duo, i don't have the model number of the motherboard on hand and was seeing if there was a way to find this information out without having to reboot and look at bios for all this information.
Comment
Watch Question

President
Top Expert 2010
Commented:
run dmidecode, which is part of most linux distributions.  It drills down into your motherboard and returns just about everything

Author

Commented:
so run command?
#dmidedcode

DavidPresident
Top Expert 2010

Commented:
yes, it just dumps to the screen, it is safe to run and does not change anything.

Author

Commented:
man, when I search trhough all the stuff trying to find the MB model, I get this:

System Information
        Manufacturer: empty
        Product Name: empty
        Version: empty
        Serial Number: empty
DavidPresident
Top Expert 2010

Commented:
So you have a no-name clone and/or that machine does not support the DMI / or AHCP. Sorry, you need to shut it off.

Author

Commented:
ok
Julian ParkerSenior Systems Administrator

Commented:
probably be easier to open the case and have a look at the mainboard.

haldevice may provide some info (if hald is running) but it could just display as a load of hex codes that will need to be translated.
DavidPresident
Top Expert 2010

Commented:
Stepping back a minute ... Unless you have a SSD, or are using a mux/expander with multiple drives on a single port, then you won't see any difference in throughput on 1.5Gbps vs 3.0Gbps anyway.

Author

Commented:
dlethe:

why is that?
DavidPresident
Top Expert 2010

Commented:
1.5Gbps basically gives you bus saturation at 150MB/sec transfer.   What SATA disk do you have that can sustain 150MB/sec?  Even the latest 7200 RPM seagate SATA2 barracuda can only sustain 120MB/sec.   Increasing the interface speed won't help you until you exceed the interface.

You are asking the equivalent of adding 2 more lanes to a 2-lane road when you are the only car using it.  
DavidPresident
Top Expert 2010

Commented:
No, you are confusing the INTERFACE speed with the disk speed.   Read the full specs.  Neither disk is capable of doing 3GB/sec.  Heck, not even the $500+ SSDs can send/receive data that fast.

Author

Commented:
ok, so with only 2 hd's doing raid1 it doesn't matter whether they're 1.5 or 3.0gbps speeds.  Only time it matters is if you have a raid10 or raid5 or something?  is that the reason for the 3gbps transfer speed?

So i'm better off just not getting anything at all, use the onboard sata-1 ports and test software raid1 to save time and money.  Then if that doesn't work, just go hardware raid and spend the time and money.
DavidPresident
Top Expert 2010

Commented:
Yes, exactly.  Mechanical disk drives can't take advantage of the faster interface (well, some can for a fraction of a second on cached reads, but in grand scheme of things, unless you use your computer for benchmarking and contrive a benchmark specifically to measure that, then you won't notice a difference).

  Remember RAID1 is no substitute for backing up.  All it takes is one stupid command and your RAID1 will gladly delete or overwrite both copies of your file(s), so save your money and invest in backup, either online, or with an external eSATA or USB attached disk if you don't already have a backup strategy.
DavidPresident
Top Expert 2010

Commented:
Plus even better, with the LINUX software RAID, it will balance read requests so that the disk that can supply the data the fastest will do so.  Even though the interface tops out at 150MB/sec, you could potentially get greater throughput.  Remember, each port is limited to 150MB/sec, your controller, as a whole, is limited to the PCI or PCIe bus interface which is much higher.

Author

Commented:
awesome!  yes we do cpanel backup.  So what I want to do is, raid1 2x 500GB hd's  just for some redundancy.  Then those backup daily, weekly, monthly to another backup drive on same machine.  Then we also do offsite backup via rsync daily, weekly, monthly of the cpanel backups.

Currently we're just using 1x drive for the main drive, so I figure raid1 would be a step up in redundancy, or am I mistaken...ie. would it just cause more worries and troubles due to more complexities?
DavidPresident
Top Expert 2010

Commented:
Yes software RAID1 is a step up in redundancy, performance, and data integrity.  One of the great things about RAID1 is that if a disk develops even a bad block, then the md driver will read that block from the other disk drive, and then automatically remap the bad block and write the correct value.   So with software (or hardware) RAID1, bad blocks automatically repair themselves.

So RAID1 is vital for data integrity, not just a drive failure.  I am sure that you have seen errors about unreadable blocks.  Now with RAID1, they will self-repair.

Author

Commented:
oh cool.  

I also read you're article about not buying consumer grade hd's.  that was very informativie thanks!.