[mythtv-users] Need advice on FC12 HD partitioning

R. G. Newbury newbury at mandamus.org
Sun Jan 3 04:07:03 UTC 2010


On 01/02/2010 10:56 AM, Jarod Wilson wrote:
> On Jan 2, 2010, at 3:28 AM, Another Sillyname wrote:
>
>> 2010/1/2 Jarod Wilson<jarod at wilsonet.com>:
>>> On Jan 1, 2010, at 12:50 PM, steve wrote:

>> 160 TB - Setup as you boot and 'working' drive
>
> Wow, you have a 160 TB drive? ;)
>
>> say 8gb swap (although it's suggested to use the amount of RAM I
>> always use RAM x 2 to allow for future memory upgrades, and let's face
>> it the difference between 4gb and 8gb on a 160gb disk is
>> insignificant).
>
> Swap is mostly worthless if you have enough memory. I don't bother with more than 2G on any system, and that's only for a safety net in the case of a run-away memory-sucking process or something. If you need more swap than that, I'm sorry, but you're Doing It Wrong. RAM x 2 for swap is a horrible guideline these days, when many systems ship with 4GB of RAM. A quick glance at the systems in my house, NONE of them are using ANY swap (all my in-use boxes have at least 4GB of RAM these days though, including both my laptops and my ion frontend).

I'll second Jarod's vote for xfs for the video. It is stable. xfs has a 
nice feature which allows the system to pre-allocate (or pre-reserve) 
really large chunks of continuous disk space for large files...like we 
keep putting down on disk. This really cuts down on fragmentation and 
speeds up deletions. Remember that the usual ext allocation is about 4K 
bytes. xfs 'holds' a half a gigabyte for the particular file (and rights 
the other files into their own allocation). Put this line in your 
/etc/fstab. (More deep in 'man mount' Max allocsize is 1G )

/dev/sdb1       /video          xfs 
users,logbufs=4,noatime,nodiratime,allocsize=512M 0 0

As to partitioning the OS drive, I use separate partitions for /boot, 
/home, /usr/local, /tmp and /var. What we want is reliability, safety 
and recoverability. But this is a home system, not a corporate server. 
And we probably want to keep the power requirements down too. And 
there's the sound thing. So RAID is overkill for tv, but we do not want 
to lose data if the OS drive dies.

I'm not sure that /boot really needs to be a separate partition, but 
inertia keeps me using it. I run svn and everything goes into /usr/local 
so I like a separate partition for the myth executables and libs, plus 
my own scripts in /usr/local/sbin.

The last 2 partitions, /tmp and /var are for safety, to protect you from 
runaway log files and other things that go bump. If you fill a 
partition, your system dies. But if it dies overwriting your main 
partition your disk is basically unrecoverable and unusable. With a /tmp 
partition, the system will actually continue to sort-of operate: your 
mythtv setup will suddenly show NO RECORDINGS!!! and NO SCHEDULED 
RECORDINGS!! Just jump to a console and delete some stuff from /tmp (or 
var) so the system can log stuff again. /var is where the logfiles go, 
especially the mythbackend logfiles.

'df -h' is your friend here, if you can remember that when your heart 
rate has just hit 150!

On Fedora, I move /var/lib/mysql/* to /home/mysql/ and symlink it. Same 
for /var/www/html (for mythweb's setup). Now everything important is on 
the /home partition (a primary partition) and not lost if you fill a 
partition. The next full install /home will likely become /dev/sda1 
(even easier to recover if necessary...'dd'??.

I have a /video/temp folder, which gets a copy of /etc, /home and 
/usr/local  by cron, daily. That backs up the database, and all the 
settings info. With the /video drive (and the database on it), you can 
re-install on completely new hardware and lose only the downtime of the 
install! My /home is only 145Meg after a couple of years, so the 
partition need not be large.  /usr/local is 1.5Gig.

Just my 2 cents. I picked up the idea of symlinking mysql and html 
(doc_root) from a mysql forum. Sounded like a good idea and it has saved 
me a couple of times.

Geoff








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