Layout SSD + 2xHDD, RAID1, LVM, dual boot with Win7, please comment

zenblu · 2010-12-12 04:12:58

Hello and thank you for reading. I am about to start installing Arch and Win7 on my new computer.

I have 3 disks:
- Intel X25-M G2 80GB SSD
- 2x Samsung Spinpoint 1TB

The PC has 8GB of RAM.

I would like to have Arch 64b as the main system and Win7 x64 in dual boot. My priorities are:
- squeeze as much performance as I can while make it ease on my SSD to give it long life
- have parts of the HDDs in RAID1 (home and important media) for more speed and improved data safety

I'm thinking of this setup:

SSD:
128MB /boot ext4 no journaling
40GB / ext4 with journaling
20GB Win7 NTFS
(~20GB ?)

HDD0:
4GB /var
500GB /home (in RAID1 with a corresponding partition on HDD1) ext4
rest ext4 for various data

HDD1:
4GB swap
500GB /home (in RAID1 with HDD0)
rest NTFS for media

in RAM:
4GB /tmpfs

1. What do you think of this setup? Is it feasible? Will I get good performance out of it while making not overburdening my SSD? Will it work well with Arch (pacman, etc.)?
2. Do you think it might make sense to split /home RAID1 into two partitions (on both drives): /home RAID1 and /important_data (like my pictures) RAID1?
3. What would you suggest me to do with the remaining space on SSD? I'm considering:
- an ext4 journaled partition for "current projects I'm working on"
- having a small /home there for the configs, profiles, settings etc. to speed up applications even further, but I am afraid that apps like Firefox would bombard my SSD with huge number of writes to their profiles
- other ideas?
4. What do you think of /var placement? I was hesitant to put in on SSD and making it into RAID1 on HDDs doesn't make sense to me, as /var is mostly written to, so wouldn't speed things up. Although /var is used by pacman, so maybe having it in RAID1 at least would actually make sense?

Thank you for any comments!

Last edited by zenblu (2010-12-12 04:18:12)

stobbsm · 2010-12-12 15:09:48

I have a similar setup, but needed 30G for my win7 partition. I tried with 20, and it was fine until reboot, then it started complaining about running out of disk space.

How are you setting up the RAID1? DMRaid? mdadm? Third party controller?

Windows can't read mdadm volumes, and linux can't use Windows Virtual Disk managed volumes.

My setup is:

Kingston 64GB SSD - 100MB system reserved (windows done), 30G win7, the rest for arch root
2xWestern Digital 320GB - RAID0 setup (need the performance more then the redundancy), 320GB for win7 apps, 200GB for /home, 100GB left over in LVM in case I need it, but I doubt I will.

I also have a server for all of my data storage needs, which consists of:
2xWestern Digital Green drives (1TB) in a RAID1 setup. The server is also my HTPC with Boxxee, but it's running Ubuntu server. probably going to switch it to arch soon.

My philosophy is that you should have your desktop performance oriented, with a server for storage. Keeps costs down, maintenance easy, and ensures your files are always available, even in Windows if you need it.

stqn · 2010-12-12 20:53:47

My thoughts:
- putting /var on the SSD would increase noticiably pacman's speed, unless maybe you're planning to use reiserfs.
- once you have disabled Firefox's disk cache or moved it to another disk (see the SSD page on the wiki), Firefox shouldn't write a problematic amount of data on the SSD.
- 40 GB for / without /home, /tmp and /var seems way overkill. Also with 8GB of RAM, swap seems useless... unless you plan to write several GB of data to tmpfs I guess.
- Keeping 20% of your SSD unused should increase noticiably its life span... So if you don't need it, don't use it! (Edit: actually I don't remember if it increases life span and/or perfomance... It should be beneficial anyway )

My setup is: 100 MB /boot (ext4), 20GB / (ext4), both on my 64GB Onyx SSD. /tmp in tmpfs (2GB of RAM total.) No disk cache for Firefox. Several USB disks for data (ext4 and NTFS.)

Last edited by stqn (2010-12-12 20:55:40)

zenblu · 2010-12-12 23:57:28

Hm... But does "not using it" cross partition boundaries? If I only had half of the SSD partitioned, would the whole memory be used interexchangeably? I.e. if I had 40 of 80GB partitioned, would the whole 80GB be still used (40GB worth of it at a time)?

Last edited by zenblu (2010-12-12 23:57:50)

stqn · 2010-12-13 01:00:26

Yes, the SSD controllers don't care about partitions or filesystems... As far as I know.

zenblu · 2010-12-13 01:10:27

Just had a good discussion about it on IRC. An OS sends TRIM commands only about partitioned blocks. As long as the controller knows, that the unpartitioned space is free, it should reuse it. But if - for one reason or another - they weren't already marked as free, they would stay unusable indefinitely. Partitioning the whole thing on the other hand should prevent this, since now the OS also knows about those blocks and we have a better chance it marks them as free. So the latter option seems safer to me, although it's just a logical assumption, I don't know the details of how controllers work.

stqn · 2010-12-13 01:54:32

Yeah, I was about to write that, but didn't . I think it's safe to assume that the whole disk is marked as free when you buy it... I also assume gparted will at some point send TRIM commands when deleting partitions, but I don't think it's already the case...

Arch Linux

#1 2010-12-12 04:12:58

Layout SSD + 2xHDD, RAID1, LVM, dual boot with Win7, please comment

#2 2010-12-12 15:09:48

Re: Layout SSD + 2xHDD, RAID1, LVM, dual boot with Win7, please comment

#3 2010-12-12 20:53:47

Re: Layout SSD + 2xHDD, RAID1, LVM, dual boot with Win7, please comment

#4 2010-12-12 23:57:28

Re: Layout SSD + 2xHDD, RAID1, LVM, dual boot with Win7, please comment

#5 2010-12-13 01:00:26

Re: Layout SSD + 2xHDD, RAID1, LVM, dual boot with Win7, please comment

#6 2010-12-13 01:10:27

Re: Layout SSD + 2xHDD, RAID1, LVM, dual boot with Win7, please comment

#7 2010-12-13 01:54:32

Re: Layout SSD + 2xHDD, RAID1, LVM, dual boot with Win7, please comment

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