Raw vs. Cooked dbspaces?
A DBA setting up a new IDS instance asked whether to use raw devices or cooked files for dbspaces, and whether the speed gain justifies the setup effort. Most replies favoured raw, arguing it's actually simpler (no filesystem to build) and noticeably faster — one poster reported a dramatic gain after converting a cooked database to raw on HP-UX 10.20. A dissenter preferred cooked chunks because raw devices are easily overwritten by admins who don't realise they're in use; suggestions included labelling raw volumes meaningfully in HP-UX SAM and benchmarking both yourself. Art Kagel pointed to numbers in the IIUG CDI archive. No single definitive answer, just a consensus leaning to raw with caveats.
Auto-generated by DrWatson from the posts below — may be imperfect; read the full thread.
Hi, I'm setting up a new IDS instance and was wondering if I should go with raw or cooked dbspaces. Can you give me some suggestions? I know that raw devices would be faster than cooked files but does anyone know how much faster? Is the extra speed worth all the initial headaches to setup the raw device partitions? Thanks a lot. Samuel Lee. Systems Analyst Trinidad & Tobago Electricity Commission. Sent via Deja.com http://www.deja.com/ Before you buy.
In article <8ge2e2$fir$1@nnrp1.deja.com>, sleesingchan@my-deja.com wrote: > Hi, > > I'm setting up a new IDS instance and was wondering if I should go with > raw or cooked dbspaces. Can you give me some suggestions? > raw. raw, raw, raw. > I know that raw devices would be faster than cooked files but does > anyone know how much faster? Depends. Usually raw is quite a bit faster than cooked, but it depends on how efficient the OS IO is. > Is the extra speed worth all the initial headaches to setup the raw > device partitions? > Headaches? I've always thought that using raw was easier since you don't have to bother with creating a UNIX filesystem. Other than that, everything is more or less the same. > Thanks a lot. > Samuel Lee. > Systems Analyst > Trinidad & Tobago Electricity Commission. > > Sent via Deja.com http://www.deja.com/ > Before you buy. > -- # unrm / ksh: unrm: not found # man cpio Sent via Deja.com http://www.deja.com/ Before you buy.
sleesingchan@my-deja.com wrote: > > Hi, > > I'm setting up a new IDS instance and was wondering if I should go with > raw or cooked dbspaces. Can you give me some suggestions? > > I know that raw devices would be faster than cooked files but does > anyone know how much faster? > Is the extra speed worth all the initial headaches to setup the raw > device partitions? I posted some numbers on the subject just last week when someone asked. Look in the IIUG Archive of CDI and search for RAW. Art S. Kagel
Hi, In addition to what Samuel said, you can overwrite accidentally an Informix database if it is a file system though you have to be careful when you configure disk-space through sam on Unix as it shows the raw volumes as unused as it is for newly created logical volumes. Cheers, Girish In article <8ge47v$gtt$1@nnrp1.deja.com>, mars1972@my-deja.com wrote: > In article <8ge2e2$fir$1@nnrp1.deja.com>, > sleesingchan@my-deja.com wrote: > > Hi, > > > > I'm setting up a new IDS instance and was wondering if I should go > with > > raw or cooked dbspaces. Can you give me some suggestions? > > > raw. raw, raw, raw. > > > I know that raw devices would be faster than cooked files but does > > anyone know how much faster? > > Depends. Usually raw is quite a bit faster than cooked, but it depends > on how efficient the OS IO is. > > > Is the extra speed worth all the initial headaches to setup the raw > > device partitions? > > > > Headaches? I've always thought that using raw was easier since you > don't have to bother with creating a UNIX filesystem. Other than that, > everything is more or less the same. > > > Thanks a lot. > > Samuel Lee. > > Systems Analyst > > Trinidad & Tobago Electricity Commission. > > > > Sent via Deja.com http://www.deja.com/ > > Before you buy. > > > > -- > # unrm / > ksh: unrm: not found > # man cpio > > Sent via Deja.com http://www.deja.com/ > Before you buy. > Sent via Deja.com http://www.deja.com/ Before you buy.
After a few years of patching informix chunks in raw devices after customers write over their data, I am becoming a proponent of cooked/filesystem chunks. It is too easy to forget that these devices are in use by the database. If you want to see if there is a speed difference, just use a simple program to write several Gigs of data to both types of devices and see who wins (you may want to try more compexity than that or simulate database I/O etc.). I don't think you will see much difference in most operating systems today. girishpunjabi@my-deja.com wrote: > Hi, > > In addition to what Samuel said, you can overwrite accidentally an > Informix database if it is a file system though you have to be careful > when you configure disk-space through sam on Unix as it shows the raw > volumes as unused as it is for newly created logical volumes. > > Cheers, > > Girish > > In article <8ge47v$gtt$1@nnrp1.deja.com>, > mars1972@my-deja.com wrote: > > In article <8ge2e2$fir$1@nnrp1.deja.com>, > > sleesingchan@my-deja.com wrote: > > > Hi, > > > > > > I'm setting up a new IDS instance and was wondering if I should go > > with > > > raw or cooked dbspaces. Can you give me some suggestions? > > > > > raw. raw, raw, raw. > > > > > I know that raw devices would be faster than cooked files but does > > > anyone know how much faster? > > > > Depends. Usually raw is quite a bit faster than cooked, but it > depends > > on how efficient the OS IO is. > > > > > Is the extra speed worth all the initial headaches to setup the raw > > > device partitions? > > > > > > > Headaches? I've always thought that using raw was easier since you > > don't have to bother with creating a UNIX filesystem. Other than > that, > > everything is more or less the same. > > > > > Thanks a lot. > > > Samuel Lee. > > > Systems Analyst > > > Trinidad & Tobago Electricity Commission. > > > > > > Sent via Deja.com http://www.deja.com/ > > > Before you buy. > > > > > > > -- > > # unrm / > > ksh: unrm: not found > > # man cpio > > > > Sent via Deja.com http://www.deja.com/ > > Before you buy. > > > > Sent via Deja.com http://www.deja.com/ > Before you buy.
Oh I know one or two Sys Admins who've mkfs'd a raw partition thinking it's not in use, not so bad if its a normal data dbspace but if its rootdbs then ... girishpunjabi@my-deja.com wrote: > > Hi, > > In addition to what Samuel said, you can overwrite accidentally an > Informix database if it is a file system though you have to be careful > when you configure disk-space through sam on Unix as it shows the raw > volumes as unused as it is for newly created logical volumes. > > Cheers, > > Girish > > In article <8ge47v$gtt$1@nnrp1.deja.com>, > mars1972@my-deja.com wrote: > > In article <8ge2e2$fir$1@nnrp1.deja.com>, > > sleesingchan@my-deja.com wrote: > > > Hi, > > > > > > I'm setting up a new IDS instance and was wondering if I should go > > with > > > raw or cooked dbspaces. Can you give me some suggestions? > > > > > raw. raw, raw, raw. > > > > > I know that raw devices would be faster than cooked files but does > > > anyone know how much faster? > > > > Depends. Usually raw is quite a bit faster than cooked, but it > depends > > on how efficient the OS IO is. > > > > > Is the extra speed worth all the initial headaches to setup the raw > > > device partitions? > > > > > > > Headaches? I've always thought that using raw was easier since you > > don't have to bother with creating a UNIX filesystem. Other than > that, > > everything is more or less the same. > > > > > Thanks a lot. > > > Samuel Lee. > > > Systems Analyst > > > Trinidad & Tobago Electricity Commission. > > > > > > Sent via Deja.com http://www.deja.com/ > > > Before you buy. > > > > > > > -- > > # unrm / > > ksh: unrm: not found > > # man cpio > > > > Sent via Deja.com http://www.deja.com/ > > Before you buy. > > > > Sent via Deja.com http://www.deja.com/ > Before you buy. -- Paul Watson # WF Software Ltd # You are only young once Tel: +44 1436 674729 # but you can be immature Fax: +44 1436 678693 # for ever www.wfsoftware.com #
SAM is a HPUX specific admin tool, it does allow you to label a raw device as used, this then shows in same in place of the "Unused" message. I generally give the raw devices a meaningful name and label them "Informix" -- --------------------------------------- Tony Flaherty aef@mfs.misys.co.uk Analyst Programmer Misys Financial Systems All statements and opinions are my own, Misys don't pay me enough to have opinions on their behalf . girishpunjabi@my-deja.com wrote in message <8gf36c$790$1@nnrp1.deja.com>... >Hi, > >In addition to what Samuel said, you can overwrite accidentally an >Informix database if it is a file system though you have to be careful >when you configure disk-space through sam on Unix as it shows the raw >volumes as unused as it is for newly created logical volumes. > >Cheers, > >Girish > > >In article <8ge47v$gtt$1@nnrp1.deja.com>, > mars1972@my-deja.com wrote: >> In article <8ge2e2$fir$1@nnrp1.deja.com>, >> sleesingchan@my-deja.com wrote: >> > Hi, >> > >> > I'm setting up a new IDS instance and was wondering if I should go >> with >> > raw or cooked dbspaces. Can you give me some suggestions? >> > >> raw. raw, raw, raw. >> >> > I know that raw devices would be faster than cooked files but does >> > anyone know how much faster? >> >> Depends. Usually raw is quite a bit faster than cooked, but it >depends >> on how efficient the OS IO is. >> >> > Is the extra speed worth all the initial headaches to setup the raw >> > device partitions? >> > >> >> Headaches? I've always thought that using raw was easier since you >> don't have to bother with creating a UNIX filesystem. Other than >that, >> everything is more or less the same. >> >> > Thanks a lot. >> > Samuel Lee. >> > Systems Analyst >> > Trinidad & Tobago Electricity Commission. >> > >> > Sent via Deja.com http://www.deja.com/ >> > Before you buy. >> > >> >> -- >> # unrm / >> ksh: unrm: not found >> # man cpio >> >> Sent via Deja.com http://www.deja.com/ >> Before you buy. >> > > >Sent via Deja.com http://www.deja.com/ >Before you buy.
Actually, I've taken an existing database on a cooked filesystem and converted it to raw. This was on HP 10.20. We tried doing a reorg first and that didn't improve performance much, but converting it to raw increased performance dramatically. In article <392B3A9D.35F08521@bellatlantic.com>, lslane <lslane@bellatlantic.com> wrote: > After a few years of patching informix chunks in raw devices after > customers write over their data, I am becoming a proponent of > cooked/filesystem chunks. It is too easy to forget that these devices are > in use by the database. If you want to see if there is a speed difference, > just use a simple program to write several Gigs of data to both types of > devices and see who wins (you may want to try more compexity than that or > simulate database I/O etc.). I don't think you will see much difference in > most operating systems today. > > girishpunjabi@my-deja.com wrote: > > > Hi, > > > > In addition to what Samuel said, you can overwrite accidentally an > > Informix database if it is a file system though you have to be careful > > when you configure disk-space through sam on Unix as it shows the raw > > volumes as unused as it is for newly created logical volumes. > > > > Cheers, > > > > Girish > > > > In article <8ge47v$gtt$1@nnrp1.deja.com>, > > mars1972@my-deja.com wrote: > > > In article <8ge2e2$fir$1@nnrp1.deja.com>, > > > sleesingchan@my-deja.com wrote: > > > > Hi, > > > > > > > > I'm setting up a new IDS instance and was wondering if I should go > > > with > > > > raw or cooked dbspaces. Can you give me some suggestions? > > > > > > > raw. raw, raw, raw. > > > > > > > I know that raw devices would be faster than cooked files but does > > > > anyone know how much faster? > > > > > > Depends. Usually raw is quite a bit faster than cooked, but it > > depends > > > on how efficient the OS IO is. > > > > > > > Is the extra speed worth all the initial headaches to setup the raw > > > > device partitions? > > > > > > > > > > Headaches? I've always thought that using raw was easier since you > > > don't have to bother with creating a UNIX filesystem. Other than > > that, > > > everything is more or less the same. > > > > > > > Thanks a lot. > > > > Samuel Lee. > > > > Systems Analyst > > > > Trinidad & Tobago Electricity Commission. > > > > > > > > Sent via Deja.com http://www.deja.com/ > > > > Before you buy. > > > > > > > > > > -- > > > # unrm / > > > ksh: unrm: not found > > > # man cpio > > > > > > Sent via Deja.com http://www.deja.com/ > > > Before you buy. > > > > > > > Sent via Deja.com http://www.deja.com/ > > Before you buy. > > -- # unrm / ksh: unrm: not found # man cpio Sent via Deja.com http://www.deja.com/ Before you buy.