Date: Wed, 04 May 2011 19:17:27 -0400 From: Daniel Staal <DStaal@usa.net> To: freebsd-questions@freebsd.org Subject: Laptop Multi-HD partitioning advice (ZFS) Message-ID: <267B4CEEF5135C2FE0F2087E@mac-pro.magehandbook.com>
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I just got notified my new Thinkpad X220 is on it's way, and I'm thinking about the best way to use it. ;) Obviously, FreeBSD with ZFS is on top of the list. (De-dup and compression on my space-limited laptop? Yes, please.) Some relevant vitals (after a couple of upgrades that are also on their way): 6GB of RAM 250GB 2.5in HDD 40GB mSATA SSD I'm planning on installing the patched version of 8.2, with the patches for ZFS v28. My idea at this point is to use the main HDD as the primary drive, with the SSD partitioned into a small[1] ZIL-device and a larger cache drive. Since it's a SSD, I don't think disk contention should be an issue for that use, and it should speed up both reads and writes. It might even reduce the amount of main-disk use that happens. (Or at least, make it happen in short bursts, and let the drive idle in between.) I might still upgrade that HDD to something larger than stock. I could go to an SSD there too (and it's on a SATA III connection, so it could be a *faster* SSD), but I think I'm more likely to go with more space if I decide to upgrade. Obviously, I'm not afraid of a weird config in this case. ;) I'm also not trying to optimize hard for space, or for any specific use-case: I tend to use a laptop for light-duty when I'm not traveling, then more heavy-duty (as well as watching movies, etc) during occasional traveling. The idea here is to let ZFS do the disk optimization. It'll probably slow down my boot times from what could be possible, but I'm hoping ZFS will do things like move a movie I'm *currently* watching to the cache drive, and let the machine shut down the hard drive. Two things I'm *not* sure what the best choices for are the swap partition, and the boot sector. Swap could be on the HDD (slow, reduces my apparent disk-space), on the SSD (fast, reduces my most valuable disk space), or in ZFS (doesn't use dedicated space, but has stability issues under heavy load). Of course I may not ever *need* much swap, as I have a fair amount of RAM. (And I don't care about crash dumps on this box.) The boot sector doesn't really matter as much; if I go with a dedicated swap partition that will probably also hold the boot sector. Otherwise, I'm leaning towards the SSD, as I'm already planning on partitioning that, and I'm less likely to pull it out. Or, of course, there may be other considerations that I've overlooked in the rest. So, I'm looking for wisdom, or other thoughts people have. ;) Daniel T. Staal [1] As per: <http://www.solarisinternals.com/wiki/index.php/ZFS_Best_Practices_Guide#Separate_Log_Devices>; ZIL devices will never use more than 1/2 of RAM, at absolute max, and in most cases will use significantly less. Fully upgraded, this machine supports 8GB of RAM, so a 4GB ZIL device would be plenty in all cases, and would probably be overkill. --------------------------------------------------------------- This email copyright the author. Unless otherwise noted, you are expressly allowed to retransmit, quote, or otherwise use the contents for non-commercial purposes. This copyright will expire 5 years after the author's death, or in 30 years, whichever is longer, unless such a period is in excess of local copyright law. ---------------------------------------------------------------
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