Adaptec 5805 speeds

[MustRotate]

Hello all,
I've just put my array in the case, started everything and I get somewhat low speeds compared to what HD Tune is showing me.

My config:
i3 530, Gigabyte H55-USB3,A-data 2x2GB DDR3-2000
Adaptec 5805+6xHitachi 2TB Deskstar Raid6 stripe size 256k
Velociraptor 150GB OS(Windows 7 Pro x64)
When I try to transfer data either from another Deskstar,from a HD103UJ Samsung or from the Velociraptor to the array I get very low speeds(12-13MBps).
Is this normal, did I do something wrong? Files that are to be transfered are large files(Blurays).

 

[GMcDonnell]

Definitely not normal. I have a 5405 (4 port version of your card) that I'm not currently using but I had it configured similarly - OS on RAID 1 array with 2 300GB 10K Veloociraptor and three 7200 RPM Seagate 1.5 TB drives in a RAID 5 array. On system transfer times were way higher, at least 80 MB/sec as were network transfer times.

I suppose the usual suggestions make sense to start - be certain you're using the latest driver, set the arrays to be adaptive read ahead and enable the write back cache. You also may have something mucked up with the OS itself.

 

[MustRotate]

This is how its set up now:



What about enable copy back mode? Should I enable that?

 

[sub.mesa]

Perhaps the controller also disables HDD write buffering; that would get you very low speeds.

But you should start with using real benchmarks; not the HDTune that should not be used on RAID arrays anyway. Try again with:
HDTune Pro "file" benchmark
AS SSD
CrystalDiskMark
SiSoftware Sandra
ATTO

These benchmarks test on the filesystem level; and thus test real performance not artificial unrealistic single-queue access patterns done by HDTune.

 

[houkouonchi]

write speeds will blow on parity raid unless your using the disk cache (write back) not write through and I am guessing this is likely your problem as your reads seem about right. Since you only get 4 drives worth of read bandwidth (two worth are skipped due to parity) I would expect read speeds of 400-450 MB/sec (which is what you get through the second half of the array but the file-copy issue is likely due to the fact your using write-through.

If you have a BBU I would enable write-back or get a BBU and enable it.

 

[sub.mesa]

Ah yes he's using parity RAID; missed that initially.

I think most hardware controllers disable write-back mode if they do not have a BBU; some even don't allow enabling write-back with no BBU present. Not recommended for arrays that store critical data, especially without backup. Getting a BBU like houkouonchi recommends would allow you to get good/reasonable write speeds without putting your data at risk.

Since you only get 4 drives worth of read bandwidth (two worth are skipped due to parity)

They can simply skip those blocks and read the next data block; keeping all drives in a RAID5 or RAID6 busy with reading only data. Depends on actual implementation of the RAID engine though, but i know at least geom_raid5 on FreeBSD does this.

Just like some RAID1 drivers only use one disk when reading, while more advanced drivers use load-balancing for reads.

 

[MustRotate]

Yes, you are right, write-back was fault.
I enabled it and now I get speeds ranging from 65-110MBps. I will buy a BBU for the controller. Any other suggestions?

 

[novadude]

Yes, you are right, write-back was fault.
I enabled it and now I get speeds ranging from 65-110MBps. I will buy a BBU for the controller. Any other suggestions?

Nope, you're now speed limited by the source of the data.