[mythtv-users] Hard Drive reliability esp. RAID issues

Travis Tabbal travis at tabbal.net
Wed Mar 10 15:18:17 UTC 2010

On Tue, Mar 9, 2010 at 4:19 PM, Graham Mitchell <gmitch at woodlea.com> wrote:

> > Are all drives on the pci-e based sata controllers? What CPU?
> There are 2 PCIe 1x cards, Sil3132 based, with 2 SATA 3GB ports on each
> card. Each port is connected to a 5 way port multiplier (so I'm expecting
> some speed reduction there too). The CPU is an older E2100, running at
> 2GHz,
> with 4GB RAM - so not exactly overpowered, but it's only running a minimal
> FC, and all it's doing is file serving.. Currently there are 17 x 500GB
> drives connected in a RAID5, and the chunk size is set to 512K, and the
> stride on the ext3 filesystem is set to 256.

My guess is that those controller cards and/or the port multipliers are
overloaded. Unfortunately, better cards get expensive fast. I'm running 2
Supermicro USAS-L8i cards, they are PCIe x4 cards and can control 8 SATA
drives directly. I have them sitting in 2 PCIe x16 slots, though I did have
to bend the brackets up to get them to fit the case. You're braver than me
with a 17 disk RAID5, I just don't trust HDDs enough for single parity with
that many drives.

I'm running OpenSolaris w/ZFS, so my setup is a little different, but the
last time I did a dd test on the array I got about 400MB/s. I'm running 2
6-disk raidz2 (RAID6) arrays stripped together. They are also 5400 RPM
drives, so I'm quite satisfied with the speed. One of these days, I'll get a
managed switch and try link aggregation so the rest of the network can get
better overall speeds to and from that server.
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