1837958 Members
3733 Online
110124 Solutions
New Discussion

Mirror swap space

 
Eric_68
Advisor

Mirror swap space

Do I have to mirror the swap space in vg00 if I am mirroring the rest?

what is the advantages and disadvantages for mirroring swap????

Thanks
8 REPLIES 8
Bharat Katkar
Honored Contributor

Re: Mirror swap space

Hi,
I would say NO. Becuase you don't have your data in SWAP. It is used by the system just like Virtual RAM or you can even call it as extended RAM. It is only used when required i.e. whenever system runs out of memory in RAM.

Regards,
You need to know a lot to actually know how little you know
Thierry Poels_1
Honored Contributor

Re: Mirror swap space

hi,

you will find several opinions on this topic in these forums.

advantage: your system keeps on running like nothin happened if your disk crashes: no data will be lost but a reboot might be required.
disadvantage: some extra disk space wasted.

I prefer to mirror swap space. The internal disk nowadays are large enough so I don't bother about a few extra MB's.

regards,
Thierry.

All unix flavours are exactly the same . . . . . . . . . . for end users anyway.
Patrick Wallek
Honored Contributor

Re: Mirror swap space

Yes, you absolutely MUST mirror swap. If swap is not mirrored and your the disk with swap goes bad, then you run the very real risk of your system crashing. ALL swap space MUST be mirrored.

Michael Tully
Honored Contributor

Re: Mirror swap space

If your primary mirror dies and your system reboots for any reason, your are history. Your system *MUST* have primary swap in which to boot.

advantages: plenty
disadvantages: if you don't I can see in my crystal ball a very long night at some point in the future.
Anyone for a Mutiny ?
T G Manikandan
Honored Contributor

Re: Mirror swap space

Definitely mirror the primary swap which is located on vg00.

The best way would be to have a minimal primary swap on the vg00 and then the required swap on one of the other VG disks.
Geoff Wild
Honored Contributor

Re: Mirror swap space

Yes - mirror your primary swap - else systme won't boot multi user if disk that you are running on fails - the mirror will have no primary swap. You will then have to configure swap manually - which is a bit of a pain at 3 in the morning...

Rgds...Geoff
Proverbs 3:5,6 Trust in the Lord with all your heart and lean not on your own understanding; in all your ways acknowledge him, and he will make all your paths straight.
A. Clay Stephenson
Acclaimed Contributor

Re: Mirror swap space

Do you have to? No. Should you? Yes. All swap space (unlike dump space which should have nothing to do with swap) should be mirrored because otherwise your system is going to crash when the disk containing the unmirrored swap volume fails. Moreover, if swap is mirrored, you can replace a failed disk "on the fly" and never shutdown assuming hot-plug disks are used.
If it ain't broke, I can fix that.
Simon Hargrave
Honored Contributor

Re: Mirror swap space

I would argue that you HAVE to mirror PRIMARY swap, in order that you can boot in the event of a disk failure.

Agree that you SHOULD mirror all swap, if you want to maintain uptime in the event of a disk failure.