Gentoo Archives: gentoo-user

From: Matthew Marlowe <matt@×××××××××××.net>
To: gentoo-user@l.g.o
Subject: Re: [gentoo-user] terrible performance with btrfs on LVM2 using a WD 2TB green drive
Date: Tue, 15 Mar 2011 06:52:37
Message-Id: 201103142350.49670.matt@deploylinux.net
In Reply to: [gentoo-user] terrible performance with btrfs on LVM2 using a WD 2TB green drive by Bill Kenworthy
1 > My problem is that LVM2 is not supported in parted which is the
2 > recommended tool to deal with this.
3 >
4 > I suspect I only need to map the individual PE to a particular start
5 > sector on each drive, not btrfs, but then there is stripe/block sizes to
6 > consider as well ... WD also are recommending 1mb sector boundaries for
7 > best performance - I can see a reinstall coming up :)
8 >
9
10 I have on my workstation:
11 2 WD 2TB Black Drives
12 5 WD 2TB RE4 Drives
13
14 Some notes:
15 - The black drives have horrible reliability, poor sector remapping, and have
16 certain standard drive features to make them unusable in raid. I would not
17 buy them again. I'm not sure how similar the green drives are.
18 - Many of the recent WD drives have a tendency to power down/up frequently
19 which can reduce drive lifetime (research it and ensure it is set
20 appropriately for your needs).
21 - Due to reliability concerns, you'll may need to run smartd to give adequate
22 pre-failure warnings
23
24 Anyhow, in my config I have:
25
26 1 RE4 Drive as Server Boot Disk
27 4 RE4 Drives in SW RAID10 (extremely good performance and reliability)
28 2 Black Drives in LVM RAID0 for disk-to-disk backups (thats about all I trust
29 them with).
30
31 When I setup the LVM RAID0, I used the following commands to get good
32 performance:
33 fdisk (remove all partitions, you don't need them for lvm)
34 pvcreate --dataalignmentoffset 7s /dev/sdd
35 pvcreate --dataalignmentoffset 7s /dev/sdf
36 vgcreate -s 64M -M 2 vgArchive /dev/sdd /dev/sdf
37 lvcreate -i 2 -l 100%FREE -I 256 -n lvArchive -r auto vgArchive
38 mkfs.ext4 -c -b 4096 -E stride=64,stripe_width=128 -j -i 1048576 -L
39 /archive /dev/vgArchive/lvArchive
40
41 I may have the ext4 stride/stripe settings wrong above, I didn't have my
42 normal notes when I selected them - but the rest of the config I scrounged
43 from other blogs and seemed to make sense (the --dataalignmentoffset 7s) seems
44 to be the key.
45
46 My RAID10 drives are configured slightly different w/ 1 partition that starts
47 on sector 2048 if I remember and extends to the end of the drive.
48
49 The 4 Disk SW RAID10 array gives me 255MB/s reads, 135MB/s block writes, and
50 98MB/s rewrites (old test, may need to rerun for latest changes/etc).
51
52 LVM 2 Disk RAID0 gives 303MB/s reads, 190MB/s block writes, and 102MB/s
53 rewrites (test ran last week).
54
55 Regards,
56 Matt
57 --
58 Matthew Marlowe / 858-400-7430 / DeployLinux Consulting, Inc
59 Professional Linux Hosting and Systems Administration Services
60 www.deploylinux.net * matt@×××××××××××.net
61 'MattM' @ irc.freenode.net

Replies

Subject Author
Re: [gentoo-user] terrible performance with btrfs on LVM2 using a WD 2TB green drive William Kenworthy <billk@×××××××××.au>
Re: [gentoo-user] terrible performance with btrfs on LVM2 using a WD 2TB green drive Florian Philipp <lists@×××××××××××.net>