1 - Is the OS really independent of the Perc card and the MD1000? Yes. The data that is stored on the MD & the configuration that you have for each host is kept on the Perc card and a copy of the meta data is on the drives incase of a failed controller you can swap it with a replacement & copy the configuration back to the new card.
2 - Does the 'cache' contain ALL the data needed to manage/run the raid configuration(s)? The Cache is used for reads & writes request of data that you are accessing from the MD. As it is faster to write the data to cache then to read & write from the drives all the time.
3 - Where does the cache live when the system is running? Where does the cache live when the system is shut down? In the OS install on the R5400? In the Perc card? In the disk subset(s) in the MD1000? The Cache is on the Perc card. The reads & writes are sent from the server to the perc card then then perc card pushes the reads & writes to the MD1200 to access the data. When the host/server is off the data that is on the perc is pushed to the MD1200 before the server powers off if the Perc battery is working. If battery is not working & you have a sudden power loss then the data may get written to the MD if on a UPS but not able to say for sure as that is what the battery is there to do.
4 - Will a questionable battery on the Perc card cause problems? Yes if you have a failed perc battery then you will not be able to use the cache feature on the Perc. The battery is needed so that it can ensure that the reads & writes get pushed to the MD. If you have a dead raid battery then you are doing direct reads & writes to the MD1200 & you will see slower through put.
5 - Where can I read more to educate myself on this topic? Here is the user manual for the Perc6e card. ftp://ftp.dell.com/Manuals/all-products/esuprt_ser_stor_net/esuprt_dell_adapters/poweredge-rc-6e_User%27s%20Guide_en-us.pdf
Here is also the users guide for your MD1200 as well. ftp://ftp.dell.com/Manuals/all-products/esuprt_ser_stor_net/esuprt_powervault/powervault-md1200_Setup%20Guide_en-us.pdf
Please let us know if you have any other questions.
Thanks very much for your info and assistance. My questions are surely simple ones. I'm learning as I go. I have re-read the user manuals for the Perc 6e card and the MD1000. The manuals have been helpful for the 'how'. Your info helps me understand the 'why'.
Along those lines, I have a couple follow-up questions.
4. Is the battery on the Perc card present to ensure complete cache transfer only during shut down and/or power loss? Or is the battery necessary for cache transfer during normal operation too? The slower direct read/writes you speak of, is this during shut down and/or power loss? Or normal operation also?
6. (new) Given my task at hand (see original post) can you recommend any precautions before I proceed? Like I said, I'm new using Perc cards and I want to avoid making a dumb mistake and losing any data.
7. (new) Is there any reading you can recommend (in addition to the user manuals) that will have the type of 'how + why' info you're kindly sending me?
4. Is the battery on the Perc card present to ensure complete cache transfer only during shut down and/or power loss? Or is the battery necessary for cache transfer during normal operation too? You need to have a working Battery to be able to use the cache feature. The slower direct read/writes you speak of, is this during shut down and/or power loss? Or normal operation also? When you have a failed perc battery the cache feature is disabled so you get direct read & writes to the drives instead of doing reads & writes of some data that can be in cache.
6. (new) Given my task at hand (see original post) can you recommend any precautions before I proceed? Like I said, I'm new using Perc cards and I want to avoid making a dumb mistake and losing any data. What I can suggest is that you have another backup solution in place just incase you run into any issues with your raid arrays like a tape backup, disk 2 disk, or offsite, etc.
7. (new) Is there any reading you can recommend (in addition to the user manuals) that will have the type of 'how + why' info you're kindly sending me? Most of the info that I have provided is from the user manual along with general raid configuration & rules.
Please let us know if you have any other questions.
DELL-Sam L
Moderator
•
7.8K Posts
0
December 27th, 2013 09:00
Hello not0294,
Here are the Answers to your questions.
1 - Is the OS really independent of the Perc card and the MD1000? Yes. The data that is stored on the MD & the configuration that you have for each host is kept on the Perc card and a copy of the meta data is on the drives incase of a failed controller you can swap it with a replacement & copy the configuration back to the new card.
2 - Does the 'cache' contain ALL the data needed to manage/run the raid configuration(s)? The Cache is used for reads & writes request of data that you are accessing from the MD. As it is faster to write the data to cache then to read & write from the drives all the time.
3 - Where does the cache live when the system is running? Where does the cache live when the system is shut down? In the OS install on the R5400? In the Perc card? In the disk subset(s) in the MD1000? The Cache is on the Perc card. The reads & writes are sent from the server to the perc card then then perc card pushes the reads & writes to the MD1200 to access the data. When the host/server is off the data that is on the perc is pushed to the MD1200 before the server powers off if the Perc battery is working. If battery is not working & you have a sudden power loss then the data may get written to the MD if on a UPS but not able to say for sure as that is what the battery is there to do.
4 - Will a questionable battery on the Perc card cause problems? Yes if you have a failed perc battery then you will not be able to use the cache feature on the Perc. The battery is needed so that it can ensure that the reads & writes get pushed to the MD. If you have a dead raid battery then you are doing direct reads & writes to the MD1200 & you will see slower through put.
5 - Where can I read more to educate myself on this topic? Here is the user manual for the Perc6e card. ftp://ftp.dell.com/Manuals/all-products/esuprt_ser_stor_net/esuprt_dell_adapters/poweredge-rc-6e_User%27s%20Guide_en-us.pdf
Here is also the users guide for your MD1200 as well. ftp://ftp.dell.com/Manuals/all-products/esuprt_ser_stor_net/esuprt_powervault/powervault-md1200_Setup%20Guide_en-us.pdf
Please let us know if you have any other questions.
not0294
3 Posts
0
December 27th, 2013 19:00
Sam,
Thanks very much for your info and assistance. My questions are surely simple ones. I'm learning as I go. I have re-read the user manuals for the Perc 6e card and the MD1000. The manuals have been helpful for the 'how'. Your info helps me understand the 'why'.
Along those lines, I have a couple follow-up questions.
4. Is the battery on the Perc card present to ensure complete cache transfer only during shut down and/or power loss? Or is the battery necessary for cache transfer during normal operation too? The slower direct read/writes you speak of, is this during shut down and/or power loss? Or normal operation also?
6. (new) Given my task at hand (see original post) can you recommend any precautions before I proceed? Like I said, I'm new using Perc cards and I want to avoid making a dumb mistake and losing any data.
7. (new) Is there any reading you can recommend (in addition to the user manuals) that will have the type of 'how + why' info you're kindly sending me?
Thanks again for the assistance.
Scott
DELL-Sam L
Moderator
•
7.8K Posts
0
January 8th, 2014 16:00
Hello Scott,
4. Is the battery on the Perc card present to ensure complete cache transfer only during shut down and/or power loss? Or is the battery necessary for cache transfer during normal operation too? You need to have a working Battery to be able to use the cache feature. The slower direct read/writes you speak of, is this during shut down and/or power loss? Or normal operation also? When you have a failed perc battery the cache feature is disabled so you get direct read & writes to the drives instead of doing reads & writes of some data that can be in cache.
6. (new) Given my task at hand (see original post) can you recommend any precautions before I proceed? Like I said, I'm new using Perc cards and I want to avoid making a dumb mistake and losing any data. What I can suggest is that you have another backup solution in place just incase you run into any issues with your raid arrays like a tape backup, disk 2 disk, or offsite, etc.
7. (new) Is there any reading you can recommend (in addition to the user manuals) that will have the type of 'how + why' info you're kindly sending me? Most of the info that I have provided is from the user manual along with general raid configuration & rules.
Please let us know if you have any other questions.