Comments on: Increase the speed of Linux Software RAID reconstruction

By: Chas

Chas — Sun, 14 Mar 2010 20:45:16 +0000

@phantomd This is why I ditched the 1.5Gbps 4-port PCI card with the crappy bios.

I looked at my options and found that a motherboard with 6 SATA ports @ 3Gbps integrated was less expensive then most good 4 port cards.

If only I’d known about using chunk sizes of 128kb or even 256kb to speed things even more. As it stands with 32kb chunks, I get about 16 to 20Mbytes/sec over Gbit Ethernet. I may swap the CPU with another machine to an Athlon64 x2 @ 2.5Ghz (65W).

Good luck

By: phantomd

phantomd — Thu, 28 Jan 2010 17:51:46 +0000

Hi
First of all thank you for this nice explanation. I am Running Fedora 10 with the Kernel 2.6.27.41-170.2.117.fc10.x86_64 my system is a core2duo 2.66Ghz, 4GB Memory, and i have a Software Raid 5 with 7×1TB running. I change the settings like described here but my reshape speed is like this :

[==>..................] reshape = 11.2% (108814776/969924224) finish=1065.4min speed=13467K/sec

I can’t get higher speed, and during the reshape if i have a look at top my system is 70% idle

I think it really depends which disk u have, which controllers are used and which kernel and distri are in use. Grrr waiting and watch

By: Chas

Chas — Thu, 14 Jan 2010 07:08:33 +0000

con’t — It turned out I’d rather just have it work, it was less expensive to get an ASROCK A780LM motherboard from Newegg, than to buy a better controller card ($62.55 USD shipped). it has 6 SATA II ports, and built in Gbit Ethernet. Now I just need to figure out why its only getting 100/Mbit link speeds. Its a great board for a file server. I just transplanted the CPU/RAM form the old one.

PCLinuxOS 2009.2 running on:
AMD Sempron 1150LE (2ghz 45W)
ASROCK A780LM integrated everything board (one IDE, 6 SATA II ports)
2GB Corsair DDR2 5300 RAM
5 WDC green 1TB SATA drives in software raid5
1 laptop 120GB SATA boot drive

The RAID transfer rate over the network is now about 9.94 Mbytes/sec, pretty close to the max for 100Mbit.

By: Chas

Chas — Sat, 09 Jan 2010 06:35:40 +0000

Well I think the problem is the sil3114, after some Googleing, I found that it has issues with drives of 1TB +

It is possible that a newer firmware on the card may help .. I have 2 cards and one I used a year or so back with some 320GB drives in SATA controller mode and it worked great, THAT card hangs after displaying the model of the first drive .. the other one seems to have been assembled with a flash chip that is not supported by the mfg’s flash utility (?!) and so it is in raid mode, however Linux still detected the drives individually (bypassing the cards firmware?!) using hdparm showed no DMA flag at all, so it is probably using PIO mode.

I will try to re-flash the first card and see if things work any better, I might find a flash chip on ebay and do a bit-o field engineering

By: Chas

Chas — Thu, 07 Jan 2010 02:10:18 +0000

I haven’t checked that, but it is difficult to imagine a modern hard drive anything like that slow, I’ll check and post more info.

By: - Marius -

- Marius - — Wed, 06 Jan 2010 18:38:17 +0000

@Chas: is the speed of the individual drives faster than what you get on the raid partition? I would say that the speed penalty of this comes from the speed of the actual drives as mdadm is very fast normally.

By: Chas

Chas — Wed, 06 Jan 2010 06:15:00 +0000

My problem is that writing or reading files to the array is extremely slow, less than 1MiB/sec
I have 5 x 1TB drives on SATA 1.5gbps ports using MDADM on a system with 1gb RAM, and a 2ghz single core AMD cpu.

Any help would be appreciated.

By: jay

jay — Wed, 07 Oct 2009 06:00:10 +0000

any ideas how to do this on a hardware or dm raid?
i’ve an 4gb reconfiguring to 6.8 and i’ve about 14 days remaining

By: Ole-Magnus

Ole-Magnus — Sat, 07 Mar 2009 01:35:53 +0000

Thank you! I was growing a full 3TB raid up to 7.5TB (6×1.5TB raid5) and it was supposed to take 15 _days_. With this tweak I’m down to ~32hours! YAY!

By: Andryan’s Random Notes » Painfully Slow CentOS System

Andryan’s Random Notes » Painfully Slow CentOS System — Sat, 06 Dec 2008 14:56:05 +0000

[...] the sync speed is only around 1000KB/s. I tried looking for solutions on Google and found this and this. The solution I got didn’t help increase the sync speed, nor the slow response I was getting [...]