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Would 3 preclears cause write speeds to drop by 50-70%? [SOLVED]

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I am writing to the cache drive (1TB SSD to SATA3 port on mobo) and I usually average around 100MBs during large file transfers (15-40GB).

 

Ran a preclear (1 cycle- 4TB) on one disk, and still maintained 100MBs the entire time (I don't remember being at my computer except during the pre read and post read :/ I believe the write occurred while I was working/sleeping).

 

Started 3 preclears (2 cycle 4tb, 3 cycle 4tb, 3 cycle 6tb) about 24 hours ago and suffered no speed loss while the prereads were happening.

 

Hop on about an hour ago and start moving more data over to the server, and I see it is running at 23MBs.

 

Things I have done so far in a fairly random order:

Check network connections.

Kill Phaze PlexMS

Reboot PC (speeds would occasionally drop to 70-80MBs and a quick reboot would get me back up to 100)

Search forums

Full Shutdown PC

Confirmed it is writing to the Cache

Yelled at monitors

Vaped some VB RSB. Clouds..

Transferred file from actual unraid share to desktop. Speed is 91-94MBs. File is 39GB

Reboot router and switch.

Search forums

search wiki

search chive.com

search google

 

Current state of 3 drives:

6tb - Zeroing (1 of 3). 22% @ 192 MB/s (23:55:50)

4tb - Post-Read (1 of 2). 16% @ 69 MB/s (23:58:15)

4tb - Post-Read (1 of 3). 16% @ 70 MB/s (23:54:19)

 

System info:

unRAID Server Pro, Version 5.0.5

Motherboard: Supermicro - X9SCL/X9SCM

Sata Controller: Supermicro something something 8 port sata2

Processor: Intel® Xeon® CPU E31230 @ 3.20GHz

Cache: Not Specified = 256 kB (max. 256 kB)

Memory: 16384 MB (max. 32 GB)

Network: eth0: 1000Mb/s - Full Duplex

Speed: 1000Mb/s

 

Any suggestions? I intend to boycott file transfers until my speeds return. My current plan is to continue vaping,yelling at my computer, & looking at the chive until the preclears are over..

 

Are any of the drives on the motherboard ports?    ... or are all involved drives on the add-in controller card?

 

You can't change it while the system's running, but I'd attach the SSD cache to a motherboard port.

 

It sounds like you've saturating the PCIe bus bandwidth available to your add-in card.    Is this an x8 card that's in a slot that only runs at x4 ??

 

  • Author

The SSD Cache is on a sata3 port on the mobo. The 6tb in preclear is on the other sata3 port on the mobo. The two 4tb drives in preclear are on sata2 ports on the mobo. My controller is completely filled with drives already in the array.

 

 

Current state of drives in preclear:

Preclear in progress... Post-Read (1 of 3). 8% @ 50 MB/s (35:27:15)

Preclear in progress... Post-Read (1 of 2). 78% @ 61 MB/s (35:29:37)

Preclear in progress... Post-Read (1 of 3). 78% @ 61 MB/s (35:25:43)

 

My transfer rate has returned. I am writing at around 97.5MBs. Still a little room for improvement, but I suspect it is the preclears that is slowing me down.

 

Thanks.

 

 

 

The post-read is always fairly slow, so those speeds look fine.  I suspect the slowdown was when the pre-clear was writing the zeroes ... that was happening at a very good speed (192Mb/s), and likely caused a slowdown when you tried to do simultaneous writes on another drive (the SSD).

 

All looks fine now ... and I suspect will remain so.

 

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