You are right saying that controller does not have memory cache neither battery. But the only thing that happens when you do not have those components is the controller works with the "Pass-Through" writing policy. It is to say, when the Operating System send a write request to the controller, it writes that request directly to the back-end disks, in this case, to both disks cause you are using RAID1 configuration.

If you had memory cache the controller would be able to use it in two ways: for read caching or write caching. For read caching, you do not have to care about having battery or not, because you won´t ever have dirty data in cache, cause it is a READ.

In the case the cache is also used for writing cache, the controller works with the "write-back" writing policy. It is to say, when the Operating System sends a write request to the controller, it writes that request to the cache memory, and afterwards, when it is able to do it, it flushes the memory content (the dirty data or pages) to the back-end disks. This procedure speeds up the system writing performance. In this case is very important to have battery in case of electrical outage, because without battery, all the dirty data that is in the cache memory is lost. BUT...the controller are smart enough to disable the "write-back" policy in case the battery does not work properly or it does not have enough charge.

So, the bottom line is. If the controller does not have cache memory, so it does not need battery (it could not use it for anything). There won´t be any data corruption because in that kind of systems there is not dirty data in memory without being written to disks (because there is not any memory to allocate that data!!!).

With cache memory, if it is used only for reading requests, it neither need battery, because there is no dirty data in memory without being written to the back-end disk, because dirty data only exists when the cache is used for write requests.

If the cache is used for writing requests, you should have battery working properly to maintain the dirty data which have not been flushed to the back-end disk in the case of electrical outage. But if battery is not OK, the controller will deactivate the cache for writing and will use it only for reading.

I hope I could help you.

Guido.

You are right saying that controller does not have memory cache nor battery. But the only thing that happens when you do not have those components is the controller works with the "Pass-Through" writing policy. It is to say, when the Operating System send a write request to the controller, it writes that request directly to the back-end disks, in this case, to both disks cause you are using RAID1 configuration.

If you had memory cache the controller would be able to use it in two ways: for read caching or write caching. For read caching, you do not have to care about having battery or not, because you won´t ever have dirty data in cache, cause it is a READ.

In the case the cache is also used for writing cache, the controller works with the "write-back" writing policy. It is to say, when the Operating System sends a write request to the controller, it writes that request to the cache memory, and afterwards, when it is able to do it, it flushes the memory content (the dirty data or pages) to the back-end disks. This procedure speeds up the system writing performance. In this case is very important to have battery in case of electrical outage, because without battery, all the dirty data that is in the cache memory is lost. BUT...the controller are smart enough to disable the "write-back" policy in case the battery does not work properly or it does not have enough charge.

So, the bottom line is. If the controller does not have cache memory, so it does not need battery (it could not use it for anything). There won´t be any data corruption because in that kind of systems there is not dirty data in memory without being written to disks (because there is not any memory to allocate that data!!!).

With cache memory, if it is used only for reading requests, it neither need battery, because there is no dirty data in memory without being written to the back-end disk, because dirty data only exists when the cache is used for write requests.

If the cache is used for writing requests, you should have battery working properly to maintain the dirty data which have not been flushed to the back-end disk in the case of electrical outage. But if battery is not OK, the controller will deactivate the cache for writing and will use it only for reading.

I hope I could help you.

Guido.

You are right saying that controller does not have memory cache neither battery. But the only thing that happens when you do not have those components is the controller works with the "Pass-Through" writing policy. It is to say, when the Operating System send a write request to the controller, it writes that request directly to the backend disks, in this case, to both disks cause you are using RAID1 configuration. If you had memory cache the controller would be able to use it in two ways: for read caching or write caching. For read caching, you do not have to care about having battery or not, because you won´t ever have dirty data in cache, cause it is a READ. In the case the cache is also used for writing cache, the controller works with the "write-back" writing policy. It is to say, when the Operating System sends a write request to the controller, it writes that request to the cache memory, and afterward, when it is able to do it, it flushes the memory content (the dirty data or pages) to the backend disks. This procedure speeds up the system writing performance. In this case is very important to have battery in case of electrical outage, because without battery, all the dirty data that is in the cache memory is lost. BUT...the controller are smart enough to disable the "write-back" policy in case the battery does not work properly or it does not have enough charge. So, the bottom line is. If the controller does not have cache memory, so it does not need battery (it could not use it for anything). There won´t be any data corruption because in that kind of systems there is not dirty data in memory without being written to disks (because there is not any memory to allocate that data!!!). With cache memory, if it is used only for reading requests, it neither need battery, because there is no dirty data in memory without being written to the backend disk, because dirty data only exists when the cache is used for write requests. If the cache is used for writing requests, you should have battery working properly to maintain the dirty data which have not been flushed to the backend disk in the case of electrical outage. But if battery is not ok, the controller will deactivate the cache for wrinting and will use it only for reading. I hope I could help you. Guido.

You are right saying that controller does not have memory cache neither battery. But the only thing that happens when you do not have those components is the controller works with the "Pass-Through" writing policy. It is to say, when the Operating System send a write request to the controller, it writes that request directly to the back-end disks, in this case, to both disks cause you are using RAID1 configuration.

If you had memory cache the controller would be able to use it in two ways: for read caching or write caching. For read caching, you do not have to care about having battery or not, because you won´t ever have dirty data in cache, cause it is a READ.

In the case the cache is also used for writing cache, the controller works with the "write-back" writing policy. It is to say, when the Operating System sends a write request to the controller, it writes that request to the cache memory, and afterwards, when it is able to do it, it flushes the memory content (the dirty data or pages) to the back-end disks. This procedure speeds up the system writing performance. In this case is very important to have battery in case of electrical outage, because without battery, all the dirty data that is in the cache memory is lost. BUT...the controller are smart enough to disable the "write-back" policy in case the battery does not work properly or it does not have enough charge.

So, the bottom line is. If the controller does not have cache memory, so it does not need battery (it could not use it for anything). There won´t be any data corruption because in that kind of systems there is not dirty data in memory without being written to disks (because there is not any memory to allocate that data!!!).

With cache memory, if it is used only for reading requests, it neither need battery, because there is no dirty data in memory without being written to the back-end disk, because dirty data only exists when the cache is used for write requests.

If the cache is used for writing requests, you should have battery working properly to maintain the dirty data which have not been flushed to the back-end disk in the case of electrical outage. But if battery is not OK, the controller will deactivate the cache for writing and will use it only for reading.

I hope I could help you.

Guido.