TiVo Community Forums Archives - Increasing swap space AFTER upgrade

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Increasing swap space AFTER upgrade
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Posted by: MrBassMan

I have already upgraded a UK TIVO by adding a 120GB hard disk but when I did the upgrade I was not aware of the >140GB problems with swap space.

I now have a 160GB TIVO with a swap space that is potentially too small to recover from disk errors. - I DO have the memory upgrade though.

My questions are:

Will the memory upgrade mean the smaller swap space is no longer a problem (Asked in another thread but with no reply)

How can I increase swap space without starting from scratch (I have a backup from before the upgrade).

I do not have a 'spare' 40GB disk lying around to backup the current A drive but I do have access to a server with loads of free space on the network. I also have TivoNet installed.

Posted by: Otto

quote:
Originally posted by MrBassMan
1) Will the memory upgrade mean the smaller swap space is no longer a problem (Asked in another thread but with no reply)

2) How can I increase swap space without starting from scratch (I have a backup from before the upgrade).

1) Possibly. Not for certain, but maybe.

2) You can't. MFS partitions cannot be resized.

Posted by: kazymyr

Not to contradict Otto, but...

If you have some unpartitioned space left on one of your drives, you can make a partition there (with pdisk) and set it as swap. I haven't done it personally, and I'm at work now so I can't look at sysinit, but it's very likely that the OS will recognize the extra swap automatically and use it (look for a line 'swapon -a' in sysinit - if it's there, then it'll work). Linux can use multiple swap partitions, or even a combination of several swap partitions and swap files (that I've done). The command to format a partition or file as swap space is 'mkswap'.

Posted by: Otto

quote:
Originally posted by kazymyr
Not to contradict Otto, but...

If you have some unpartitioned space left on one of your drives, you can make a partition there (with pdisk) and set it as swap. I haven't done it personally, and I'm at work now so I can't look at sysinit, but it's very likely that the OS will recognize the extra swap automatically and use it (look for a line 'swapon -a' in sysinit - if it's there, then it'll work). Linux can use multiple swap partitions, or even a combination of several swap partitions and swap files (that I've done). The command to format a partition or file as swap space is 'mkswap'.

Kaz: agreed, but if you use the normal methods to upgrade (Tivomad, bless and add, etc) then there is no "unpartitioned space" left to do this with.

Posted by: dmd

The last post assumes that the only place to reclaim space from is the MFS partitions. Another way would be to delete the alternate root partition and recreate it a little smaller, then use the extra space to make a new swap partition. This assumes that all the right Linux tools are available for this (fdisk, mkfs.ext2, mkswap etc.) I don't have access to my TiVo right now so I can't check. If I remember rightly, the root partitions are not very big, but also not particularly full, and it should be possible to grab, say, 50MB? Of course we might be on dangerous ground because there's no guarantee that a future release might not need a lot more space on /.

I wonder also if there are any tools (sar, top etc.) installed to monitor swap usage. If so, I could write a little script to log swap usage to a file, to find out if swap is indeed a problem on a particular TiVo.

Posted by: kazymyr

Okay, although I'm sure I saw some leftover space on a TiVoMadded drive (24M or so). Even if there's no 'partitionable' space left, you can still create an extra swap file somewhere (say, in /var) and use that as a swap supplement.

Posted by: MrBassMan

Would a swap space in /var be available during disk checking when I assume only the minimal number of partitions are mounted and even then I guess they would be mounted in a special mode to allow the disk checker a higher degree of access?

Posted by: kazymyr

I don't have first-hand experience with this, but I assume /var would be available, and read-write, in any situation. The only caveat is that it may be wiped out and rebuilt first, in which case the extra swap file would be gone. That's why an extra swap partition is better (and also for performance).

Posted by: MichaelK

is there any point to making the swap space larger than even tivomad does? Would that boost performance in any way (maybe even just a possibility in the future?)

Posted by: MrBassMan

It won't improve performance. The only thing increasing swap space does is reduces the likelyhood of getting 'out of memory' errors. A 'good' application will cope with an out of memory error.

My problem is that the disk checker program is supposedly not good at handling out of memory errors as it is reported to crash.

As I have increased my disk capacity and have not increased swap space, I may a problem if my Tivo decides to do a disk check; the checker needs more memory to work with the larger disks.

My saving grace may be the fact that I have installed extra REAL memory and so a bigger swap space may not be needed. I emphasis MAY. - All fingers, toes and eyes are crossed!

Posted by: puppypuppy

I have DTIVo that I upgraded with a new 120 GB drive (added to the existing 40 GB) so ... I have 160 GB total.

Is this swap space problem also true for DTiVo's? I know that DTiVo have more memory to begin with and that they could be configured differently.

Any comments?

Posted by: kazymyr

Swap space is like an insurance policy - it makes sure that if something bad happens, you'll have a way out of it. It will not improve performance, etc. Increasing it too much won't do any extra good, only waste space. Again, just like insurance. :)