I sent this a couple days ago, wondering if it fell through the cracks or if I am asking the wrong questions.
------
I will preface this by saying I only need about 100MB/s out of my array
because I access it via a gigabit crossover cable.
I am backing up all of my information right now (~4TB) with the
intention of re-creating this array with a larger chunk size and
possibly tweaking the file system a little bit.
My original array was a raid6 of 9 WD caviar black drives, the chunk
size was 64k. I use USAS-AOC-L8i controllers to address all of my drives
and the TLER setting on the drives is enabled for 7 seconds.
storrgie@ALEXANDRIA:~$ sudo mdadm -D /dev/md0
/dev/md0:
Version : 00.90
Creation Time : Wed Oct 14 19:59:46 2009
Raid Level : raid6
Array Size : 6837319552 (6520.58 GiB 7001.42 GB)
Used Dev Size : 976759936 (931.51 GiB 1000.20 GB)
Raid Devices : 9
Total Devices : 9
Preferred Minor : 0
Persistence : Superblock is persistent
Update Time : Mon Nov 2 16:58:43 2009
State : active
Active Devices : 9
Working Devices : 9
Failed Devices : 0
Spare Devices : 0
Chunk Size : 64K
UUID : 53dadda1:c58785d5:613e2239:070da8c8 (local to host
ALEXANDRIA)
Events : 0.649527
Number Major Minor RaidDevice State
0 8 65 0 active sync /dev/sde1
1 8 81 1 active sync /dev/sdf1
2 8 97 2 active sync /dev/sdg1
3 8 113 3 active sync /dev/sdh1
4 8 129 4 active sync /dev/sdi1
5 8 145 5 active sync /dev/sdj1
6 8 161 6 active sync /dev/sdk1
7 8 177 7 active sync /dev/sdl1
8 8 193 8 active sync /dev/sdm1
I have noticed slow rebuilding time when I first created the array and
intermittent lockups while writing large data sets.
Per some reading I was thinking of adjusting my chunk size to 1024k, and
trying to figure out the weird stuff required when creating a file system.
Questions:
Should I have the TLER on my drives enabled? (WDTLER, seven seconds)
Is 1024k chunk size going to be a good choice for my purposes? (I store
use this for storage of files that are 4MiB to 16GiB)
Is ext4 the ideal file system for my purposes?
Should I be investigating into the file system stripe size and chunk
size or let mkfs choose these for me? If I need to, please be kind to
point me in a good direction as I am new to this lower level file system
stuff.
Can I change the properties of my file system in place (ext4 or other)
so that I can tweak the stripe size when I add more drives and grow the
array?
Should I be asking any other questions?
Thanks a ton, this is the first mailing list I have ever subscribed, I
am really excited to see what you all say.
--
Andrew Dunn
http://agdunn.net
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