# sdparm or hdparm with 3Ware RAID

## ReD-BaRoN

Hi,

My 3Ware 7506-4LP uses ATA-133 disks, however the RAID itself is recognized as a SCSI device (i.e. /dev/sda). Which disk config utlity should I be using, hdparm or sdparm? Will either have an effect on the RAID array?

Thanks!

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## suicidal_orange_II

I'd say whichever the kernel sees (SCSI) but I've never tried.  If this is a hardware raid card then it might automatically configure for best performance, Timing buffered disk reads should be around 100mbps+ for 2 ATA 133 drives.  

```
hdparm -tT /dev/sda
```

and see what you get, if its low you need to do something  :Smile: 

Hope that helps,

Suicidal_Orange

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## Dieter@be

if the raid array shows up as /dev/sda, then it's just 1 (big) sata (scsi) hard-disk as far as linux is concerned  :Smile: 

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## ReD-BaRoN

 *suicidal_orange_II wrote:*   

> Timing buffered disk reads should be around 100mbps+ for 2 ATA 133 drives. 

 

Mb or MB? Are you talking RAID 0 or any RAID? (I'm running RAID 5) 

 *suicidal_orange_II wrote:*   

> 
> 
> ```
> hdparm -tT /dev/sda
> ```
> ...

 

Hmmm, these don't look so good:

```
localhost ~ # hdparm -tT /dev/sda

/dev/sda:

 Timing cached reads:   392 MB in  2.00 seconds = 195.93 MB/sec

 Timing buffered disk reads:  120 MB in  3.03 seconds =  39.55 MB/sec
```

Unfortunatly, running hpdarm commands on /dev/sda, i.e. the array fails  :Sad: :

localhost ~ # hdparm -d1 -u1 -c1 -m16 /dev/sda

```
/dev/sda:

 setting 32-bit IO_support flag to 1

 HDIO_SET_32BIT failed: Invalid argument

 setting multcount to 16

 HDIO_SET_MULTCOUNT failed: Invalid argument

 setting unmaskirq to 1 (on)

 HDIO_SET_UNMASKINTR failed: Invalid argument

 setting using_dma to 1 (on)

 HDIO_SET_DMA failed: Invalid argument

 HDIO_GET_MULTCOUNT failed: Invalid argument
```

Any ideas?

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## suicidal_orange_II

Its a SCSI device, so you should be using sdparm, no idea on the flags as I have no SCSI or SATA here.

I meant to write MB/s instead of mbps (had networking hat on   :Razz:  ) and as I get ~60MB/s on a single ATA 100 drive 39MB/s from a raid array cant be good...  

Raid varies in speed on the type, I didnt think you could do raid 5 with only 2 drives but if you say you are... raid 5 is usually used with 4 or more drives as a high performance and high redundany (any drive can fail and the data be restored), with 2 drives its usually raid 0 (which I was assuming) which should roughly double speed or raid 1 (mirroring) which allows 1 drive to fail.  

Raid 5 on 2 drives should definately be quicker than 39MB/s though, so sdparm it   :Very Happy: 

Suicidal_Orange

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## ReD-BaRoN

 *suicidal_orange_II wrote:*   

> Its a SCSI device, so you should be using sdparm, no idea on the flags as I have no SCSI or SATA here.
> 
> Raid 5 on 2 drives should definately be quicker than 39MB/s though, so sdparm it  
> 
> Suicidal_Orange

 

I'm running 3 x 300G drives.  I'll play around with sdparm and see what I can figure out.

Thanks!

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## Dieter@be

 *suicidal_orange_II wrote:*   

> raid 5 is usually used with 4 or more drives as a high performance and high redundany (any drive can fail and the data be restored), with 2 drives its usually raid 0 (which I was assuming) which should roughly double speed or raid 1 (mirroring) which allows 1 drive to fail.  
> 
> Raid 5 on 2 drives should definately be quicker than 39MB/s though, so sdparm it  
> 
> Suicidal_Orange

 

fyi, raid  5 arrays are possible from as little as 3 disks.  Also, the redundancy is not *that* high (especially on bigger arrays) in comparision to e.g. raid1 arrays where there is 50% redundancy (instead of just 1 disk with raid5), or even raid6 with 2 disks (expensive), or any combination with raid1, eg 10, 01, or a mirror (raid1) array of 2 raid 5 arrays  :Smile:   Performance is not very high btw, reads are usually decent, but writes on a raid 5 array are really slow compared to for example stripe or mirroring arrays, (because of all the parity information that needs to be read and rewritten), a good caching mechanism can help here quite a bit, but still...

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## suicidal_orange_II

 *Quote:*   

> raid 5 arrays are possible from as little as 3 disks

  dont you only have 2? This is probably getting beyond me after that, but ill learn from what follows...

I wish you well but cant really help beyond this

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## ReD-BaRoN

 *suicidal_orange_II wrote:*   

>  *Quote:*   raid 5 arrays are possible from as little as 3 disks  dont you only have 2? This is probably getting beyond me after that, but ill learn from what follows...
> 
> 

 

I'm using three disks, see above post.

Thanks!

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