# Timeout - write_dma



## mapcorp (Jun 16, 2011)

Hi,

I recently installed FreeBSD 8.2 as a guest on my Xen Server 5.5.

I'm experiencing a lot of freezes for about 3 or 4 seconds and I get DMA Timeouts like these: 

```
Jun 16 08:56:18 www1 kernel: ad0: TIMEOUT - WRITE_DMA retrying (1 retry left) LBA=7000596
Jun 16 08:57:19 www1 kernel: ad0: TIMEOUT - WRITE_DMA retrying (1 retry left) LBA=12314484
Jun 16 09:00:56 www1 kernel: ad0: TIMEOUT - READ_DMA retrying (1 retry left) LBA=12160756
Jun 16 09:01:21 www1 kernel: ad0: TIMEOUT - READ_DMA retrying (1 retry left) LBA=12160612
Jun 16 09:07:32 www1 kernel: ad0: TIMEOUT - WRITE_DMA retrying (1 retry left) LBA=4154996
Jun 16 09:13:31 www1 kernel: ad0: TIMEOUT - READ_DMA retrying (1 retry left) LBA=9086004
```

In that Xen Server I already have some other Linux machines (which use the same hard disk) and do not have that type of errors.

There's anything I can do? How can I check if the disk is really failing?

Thanks.


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## mav@ (Jun 17, 2011)

Old ata(4) subsystem (default on 8.x) has quite aggressive command timeouts. Can't it be that your physical disk is too busy to handle requests in a reasonable time? If your disk is indeed failing, you should check for it with the host OS, not with the guest.


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## dum (Jun 24, 2011)

The message I receive is:  
	
	



```
timeout waiting for write DRQ
```
Is it related? I have an old model SATA controller Promise TX4 SATA300. I'm quite sure it is a driver issue, as I'm having the problem with FreeBSD 8.2-RELEASE-p1 but not with lower ones... Any advice?


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## mav@ (Jun 24, 2011)

I think not. I've seen number of reports from Promise TX4 SATA300 users. But without any docs and hardware I can't recommend something.


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## dum (Jun 24, 2011)

I'm sorry: http://forums.freebsd.org/showthread.php?t=24099


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## gkontos (Jun 24, 2011)

dum said:
			
		

> I'm sorry: http://forums.freebsd.org/showthread.php?t=24099


In that thread I had written that I didn't have any major issues with that controller. Well, I was wrong, very wrong! Have a look at this relevant PR. To make a long story short, I have replaced three disks on that controller. The first one did indicate some issues with smartmon tools. The other two showed nothing. So, I suspected that there is something wrong with the controller.


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