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revmrblack 06-03-2015 10:30 AM

Installing Fedora21 on two drives 120G SSD and 2TB HDD, how to partition?
 
I am installing Fedora 21 on a 64 bit i7, and anaconda would not let me partition the way I wished. What I want is: on SSD 120GB swap 8GB, boot 1 GB, / 110 GB; on HHD 2TB /home 1.98 TB. The SSD is sdb, and the 2 TB is sda. Anaconda installs the / on sda (HDD) if I select both drives for the installation, even though I mark the sdb (SSD) as the boot drive.

I am able to put boot, swap, and / on the sdb (SSD) if I only tell anaconda to use that single drive. (This is my present set up with a useless 2TB HDD. My restore requires 500 GB which fails as the SSD is insufficient.) In this case it also puts /home on the SSD which is obvious. If I cannot do what I want above, how would I extend the /home on the SSD to include the 2 TB HDD? Presently the partition table shows me the following:

Thank You in Advance.

TobiSGD 06-03-2015 12:00 PM

If all your problems are caused by the large disk being detected as sda and the SSD detected as sdb the problem can simply be solved by switching ports on the motherboard, connect the SSD to the first port and the mechanical disk to the second.

EDDY1 06-03-2015 12:36 PM

@TOBISGD
Wouldn't it be better for swap to be on 2TB drive, because of all the writes?

273 06-03-2015 12:48 PM

Quote:

Originally Posted by EDDY1 (Post 5371601)
@TOBISGD
Wouldn't it be better for swap to be on 2TB drive, because of all the writes?

Indeed, RAM isn't all that expensive so if you need more then buy more. Using an SSD for swap seems in some way self-defeating.
As to the original problem -- if Anaconda is that broken have you tries filing a bug report? I suspect you may have missed the extremely well-hidden additional installer options.
I think Red Hat hide the install options so people think they need to pay for support.

John VV 06-03-2015 01:44 PM

how is the 2 tb drive partitioned ?
is it using a GPT or DOS table
or is that 2tb drive STILL!!! the factory set MICROSOFT NTFS !!!

if it is using the windows NTFS format
you can NOT use it for /home

fedora needs it to be ext4 format

TobiSGD 06-03-2015 01:48 PM

Quote:

Originally Posted by EDDY1 (Post 5371601)
@TOBISGD
Wouldn't it be better for swap to be on 2TB drive, because of all the writes?

Quote:

Originally Posted by 273 (Post 5371607)
Indeed, RAM isn't all that expensive so if you need more then buy more. Using an SSD for swap seems in some way self-defeating.

With modern SSDs (basically everything build in the last 3 years) wear-out due to excessive writing is a non-issue, for many SSDs a projected lifetime of 5 years would mean that you have to write above 30GB a day to them, this will hardly ever happen on desktop systems with SSDs of the size the OP has.
Regarding swap on the SSD or the mechanical disk, if your machine ever hits swap (which also is not common on modern desktop systems, another point why having swap on a SSD will not have much impact on lifetime) you will want to have it on the fastest storage device available to at least somewhat mitigate the performance impact that will occur in that case.

Of course 273 is right in a way, your machine should be built to fit the task, which means that you always should have the RAM dimensioned so that it fits the entire workload into RAM, if possible, but even then something unplanned might happen (like a memory leak) that will let you hit swap and, again, if that ever happens you want your swap to be as fast as possible. That doesn't mean that a fast SSD should be used as replacement for buying more RAM if needed.

273 06-03-2015 02:50 PM

I'm not convinced that swap ought to be as fast as possible and my comment was due more to the fact that using an SSD as swap is then reducing disk performance as you're potentially caching parts of the disk in RAM then swap (OK, perhaps not quite but, still).
To my mind swap in a modern desktop, at least, ought to be used only for memory leaks or hibernating -- neither of which should necessitate the use of valuable SSD space.

TobiSGD 06-04-2015 04:15 AM

Quote:

Originally Posted by 273 (Post 5371691)
to the fact that using an SSD as swap is then reducing disk performance as you're potentially caching parts of the disk in RAM then swap (OK, perhaps not quite but, still).

Caches are never swapped (wouldn't make sense at all) and never cause swapping, if there is need for more application-usable memory then cache is freed, always.

syg00 06-04-2015 04:43 AM

Quote:

Originally Posted by revmrblack (Post 5371537)
I am able to put boot, swap, and / on the sdb (SSD) if I only tell anaconda to use that single drive. (This is my present set up with a useless 2TB HDD. My restore requires 500 GB which fails as the SSD is insufficient.) In this case it also puts /home on the SSD which is obvious. If I cannot do what I want above, how would I extend the /home on the SSD to include the 2 TB HDD?

I suspect 273 is right in that you may have missed the "Advanced" partitioning option (or whatever it's called). However, if they use the same installer as CentOS 7, managing the disks is almost impossible.

Install to just the SSD, then partition the big disk as you want. Then you'll need to mount it, copy the current /home, and remount the new as your now bigger /home. Have a read of this. It's for Ubuntu, but the steps are the same.
See if you can post that partition table now - if not TobiSGD may be able to help.

273 06-04-2015 12:25 PM

Quote:

Originally Posted by TobiSGD (Post 5371955)
Caches are never swapped (wouldn't make sense at all) and never cause swapping, if there is need for more application-usable memory then cache is freed, always.

Sorry, I'd the old Windows schenario in mind.
I stand by the general idea though that it seems wasteful to lose expensive SSD space to swap when if you're using swap you're probably either hibernating, have a memory leak, or are over-extending and can probably live with the background things being in swap on a spinny thingy.

TobiSGD 06-04-2015 12:50 PM

Quote:

Originally Posted by 273 (Post 5372139)
I stand by the general idea though that it seems wasteful to lose expensive SSD space to swap when if you're using swap you're probably either hibernating, have a memory leak, or are over-extending and can probably live with the background things being in swap on a spinny thingy.

And of course this is a valid objection, one has to consider if having fast swap is outweighed by the costs of the space on a SSD (a 120GB SSD is about 70€ here, so the 4GB of swap for the average desktop computer to hibernate would come down to about 2.33€, if my math is right). That is up to the OP to decide.
Regarding the over-extending thing, there is no guarantee that only the background tasks get swapped out, if the workload is large enough even parts of the foreground process will be swapped out and in that case you want that to be as fast as possible. But again, this is unlikely to happen on the usual desktop system.

From a purely technical point, I recommend to put swap on the SSD, even if you just use it for hibernating (so that you get a faster start than with a mechanical disk, though you might get an even faster start with not hibernating).

273 06-04-2015 01:14 PM

I concede you have a point. Your numbers dob't lie so I'll not try to suggest otherwise. SSD swap still doesn't make sense to me though -- setting SSD space aside in case of a problem seems odd.

TobiSGD 06-04-2015 01:23 PM

Quote:

Originally Posted by 273 (Post 5372168)
setting SSD space aside in case of a problem seems odd.

Not more odd then reserving the slowest storage device for swap, I would think. ;)
But as I said, everyone has to make that decision based on own preferences and your view on that topic is as valid as mine.

273 06-04-2015 02:51 PM

Quote:

Originally Posted by TobiSGD (Post 5372173)
Not more odd then reserving the slowest storage device for swap, I would think. ;)
But as I said, everyone has to make that decision based on own preferences and your view on that topic is as valid as mine.

Indeed, perhaps I ought to have said "seems odd to me". I can't fail your logic.

revmrblack 06-08-2015 12:56 PM

mSATA so cable position doesn't change designation
 
Quote:

Originally Posted by TobiSGD (Post 5371581)
If all your problems are caused by the large disk being detected as sda and the SSD detected as sdb the problem can simply be solved by switching ports on the motherboard, connect the SSD to the first port and the mechanical disk to the second.

I did swap the cables on the motherboard and still have the designation sda for the HDD, and sdb for the SSD. The tech at System76 told me this would be the case because I have an mSATA drive. Till now I had not heard of mSATA.

I think I should do the install of Fedora21 on the SSD, then mount the HDD and extend the /home from the SSD to the HDD. But I don't know how to do this. Any advice?

Thanks, Jeff


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