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LSI SATA Raid - slow

Hi all,

I'm building a backup server for a client - straight forward as far as software goes - samba share for the daily backups to go into. Minimal install plus sarge.

Hardware is a 2ghz Celeron (P4 type), 256MB ram, and four Seagate 160GB SATA discs in a RAID-5 on this controller:

000:00:07.0 RAID bus controller: LSI Logic / Symbios Logic MegaRAID (rev 01) Subsystem: LSI Logic / Symbios Logic MegaRAID SATA 150-6 RAID Controller
      Flags: bus master, 66Mhz, slow devsel, latency 32, IRQ 11
      Memory at ef000000 (32-bit, prefetchable) [size=64K]
      Capabilities: [80] Power Management version 2

The card uses the LSI raid chip for raid, and three Silicon Image 3112a chips for SATA itself. I have a Sil_3112a card and I know it works as it should.

I copied the data that was on the original RAID set (3 discs) off to a 200gb Seagate PATA disc, and mc reported on the large files 27mb/s sustained write.

Now, copying stuff back to the RAID set, mc reports a mere 6-7mb/s.

The only thing that struck me as weird is that the controller didn't take much time to create the raid - less than a minute. Last time I made a raid (2 10krpm SCSI 74gb discs on an Adaptec card) that took a couple of hours. It seems like this controller does it in the background, because I can constantly hear the discs going krr krr krr. But it's been doing that since friday, and I would have thought it should be done by now.

Any ideas why I'm getting this? 7mb/s write is not going to be enough to copy all the data before the next backup starts.


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