N40L Server write speed with cache hard disk

[[email protected]]

Hello,

 

I`m new in this forum, as well as unRaid is pretty new for me. At the moment I`m running a HP N40L microserver with OPenmediavault, but without any Raid functionallity for video, mp3 storage, but also as a backup media for 3 other Windows7 computers. I have 8 hard disks (5 internal) and 4 external connnected via eSata (using portmuliplier). At the moment I`m interessted using unRaid, due to the fact it`s similar to an Raid 5 system, but without the disadvantage of loosing all data, if more than 2 hard disks crashes at the same time. Now I come to my questions: Which is the write speed I can expect with a cache hard disk, without I tested it already, its appr. 25M? Is it worth to install a SSD instead a fast 7.200 hard disk? And the last question is: is it possible to configure the cache hard disk, to write to the other hard disk and in parallel to the parity disk, when I download large files from my external computer to the unRaid system. What is the expected speed, due to I can`t test it at the moment with the free version of unRaid and I would like to have an impression befor buying the software.

 

Many thanks in advance

Dieter

[neilt0]

I get 40 to 60MB/sec on an old, slow cache drive. I'm sure others have had faster speeds.

[WeeboTech]

is it possible to configure the cache hard disk, to write to the other hard disk and in parallel to the parity disk, when I download large files from my external computer to the unRaid system. What is the expected speed, due to I can`t test it at the moment with the free version of unRaid and I would like to have an impression before buying the software.

 

Not sure I really understand this question.

 

The cache drive is in place for the fastest possible writes, skipping the data/parity disks.  There's no way to do parallel writes.

 

If you want to write to the data & parity disk, you can write directly to the disk share.

[[email protected]]

is it possible to configure the cache hard disk, to write to the other hard disk and in parallel to the parity disk, when I download large files from my external computer to the unRaid system. What is the expected speed, due to I can`t test it at the moment with the free version of unRaid and I would like to have an impression before buying the software.

 

Not sure I really understand this question.

 

The cache drive is in place for the fastest possible writes, skipping the data/parity disks.  There's no way to do parallel writes.

 

If you want to write to the data & parity disk, you can write directly to the disk share.

 

Many Thanks,

I thought It could be possible to write data to the cache disk and in parallel start the task of writing the received data directly to the data abd parity hard disks, with a slower speed, this is clear, but without any delay. The advantage of my idea is that I do not have to configue the write pass through process at a fixed time, e.g. 3am?

[itimpi]

I thought It could be possible to write data to the cache disk and in parallel start the task of writing the received data directly to the data abd parity hard disks, with a slower speed, this is clear, but without any delay. The advantage of my idea is that I do not have to configue the write pass through process at a fixed time, e.g. 3am?

You can always start the mover process manually at any time.

[UhClem]

You want to allow the caching itself to complete, before starting the mover procedure. Otherwise, the simultaneous writing to, and reading from, the cache drive will cause its disk head assembly to "thrash" (lots of seeking), and its actual data throughput will nosedive.

 

You won't have this concern IF you use a SSD for cache, but that is up to your own cost-benefit analysis. In this case, is there a chance that the mover will think it has "finished" when it has only "caught up to" the caching??

 

[dgaschk]

Use a SSD and set the mover to run often. The mover will move any files that are not open. Writing speed to the SSD should only be limited by Ethernet or the source drive.

[Automatic]

Use a SSD and set the mover to run often. The mover will move any files that are not open. Writing speed to the SSD should only be limited by Ethernet or the source drive.

 

root@Tower:~# dd if=/dev/zero of="/mnt/user/Nicks Files/DeleteMe" bs=4096 count=1000000
1000000+0 records in
1000000+0 records out
4096000000 bytes (4.1 GB) copied, 60.9781 s, 67.2 MB/s

 

Model=Samsung SSD 840 Series, FwRev=DXT06B0Q, SerialNo=XXX

 

/whistle.

 

EDIT:- Did the test again:-

512000000 bytes (512 MB) copied, 53.6765 s, 9.5 MB/s

 

/Whistle even harder.

 

Something is obviously wrong with my box :'(

[WeeboTech]

Where do you have the SSD connected?

Perhaps post a syslog.

 

Did you reflash the ROM?

if so, did you follow the instructions for disabling IDE mode on the "other" ports.

 

FWIW, I purchased a 2 port 6GB/s X1 PCIe 2.0 ASMEDIA card so I could get the maximum speed out of my SSD.

 

Please do a read test and post results.

dd if=/dev/sd? of=/dev/null bs=4096 count=1024000

 

Where ? = actual SSD drive device.

 

This will be your maximum read speed outside of any filesystem handling.

 

You can then do a test directly to the cache drive outside of the fuse/shfs environment with a similar command as below.

 

dd if=/dev/zero of="/mnt/cache/DeleteMe" bs=4096 count=1024000

 

If you are in IDE mode you will max out around 120MB/s.

 

My samsung PM840 with the ASMEDIA SATA III gets around 300-350MB/s raw read speeds.