Extremely slow SATA performance.

sand_man · 2009-08-17 23:33:37

Hi guys,

My new hard drive is a Seagate 1TB SATA. The problem is that this old PC I'm using as a server doesn't have SATA ports so I have to use an IDE to SATA adapter.

So my setup is like this:

40GB IDE which has the system installed on it.
500GB IDE which is LVM with multiple partitions.

and my new 1000GB SATA (via IDE port) which is also LVM and is an extension of one of the partitions of the 500GB LVM disk.

When I copy anything from the 500GB it is fine, no problems at all.
The problem only seems to be with the partition that is spread across both disks.
If I read or copy a file that was on the partition before the new disk was added, its fine.
If I read or copy a file which was only added to the partition since the new disk was added, it is extremely slow and I can see the average load go up and up until my ssh session drops out.

At the moment I'm trying to copy back the files I added recently, to another disk so that I can remove the new disk from the volume group, just in case the problem is that the files are spread across two disks. I have copied about 5MB in the last half hour

hdparm reports the following:
sdb = 40GB operating system drive
sda = 500GB IDE
sdc = 1000GB SATA - problematic

sudo hdparm -Tt /dev/sdb

/dev/sdb:
 Timing cached reads:   620 MB in  2.00 seconds = 309.29 MB/sec
 Timing buffered disk reads:  132 MB in  3.00 seconds =  43.98 MB/sec

sudo hdparm -Tt /dev/sda

/dev/sda:
 Timing cached reads:   308 MB in  2.00 seconds = 153.65 MB/sec
 Timing buffered disk reads:    8 MB in  3.87 seconds =   2.07 MB/sec

sudo hdparm -Tt /dev/sdc

/dev/sdc:
 Timing cached reads:   608 MB in  2.00 seconds = 303.88 MB/sec
 Timing buffered disk reads:  234 MB in  3.01 seconds =  77.61 MB/sec

As you can see there doesn't seem to be a problem with the read speed of /dev/sdc

Does anyone have any suggestions?

Last edited by sand_man (2009-08-17 23:34:25)

sand_man · 2009-08-18 00:09:17

After further testing, there doesn't seem to be a slowness problem with that drive other than the few large files which were recently added. Because of their size they are most likely spread across both disks.
How the hell did I get them there in the first place?
I don't know what to do know.

sand_man · 2009-08-20 23:36:27

Update (sad face)

See the hdparm benchmarks up there? ^^
/dev/sda is slow. Why? Because it was dying and I failed to notice. It wasn't the SATA drive with the problem at all.
Now I've lost 500GB of data.

I'm gonna go hang my self in my closet now...

edit:

I'm tempted to try this trick...http://forums.freebsd.org/showthread.php?t=6356

Last edited by sand_man (2009-08-21 01:23:41)

Arch Linux

#1 2009-08-17 23:33:37

Extremely slow SATA performance.

#2 2009-08-18 00:09:17

Re: Extremely slow SATA performance.

#3 2009-08-20 23:36:27

Re: Extremely slow SATA performance.

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