On Thu, Feb 27, 2014 at 7:17 AM, Rainer Traut tr.ml@gmx.de wrote:

Hi,

I am running C6.5 64bit on an USB stick connected to a HP DL360G7;

You mean flash memory? (And not a conventional spinning disk drive in an external enclosure.) Yikes.

It is usually an ESXi host but eg for firmware updates (not available on SPP) I use this local installation.

Problem are the lags and unresponsiveness we are seeing for example when running yum update in the installation phase. The whole system stalls but there is no io in vmstat.

From what google tells us, this is a known problem with linux. But is there anything we can do to mitigate?

steps so far: mount / with ext4: defaults,data=writeback,noatime,nodiratime

Noatime and nodirtime are a step in the right direction to reduce writes on the flash mem.

If you are indeed on flash memory (and not something reliable like an SSD), you probably want to ditch journaling. Journaling is likely killing your usb stick. So mount as ext2 rather than ext4.

For flash memory it's a good idea to tune the number of checks until fsck is forced. tune2fs -c0 /dev/sdX

There are projects tailored for flash memory (think Voyage Linux) which put certain items in memory (not on flash) while running. In Voyage's case it sets the flash mem partitions to RO and you can only write to those partitions if you enable RW (I expect it switches to RW on shutdown to write certain files).

You're probably better off going with an SSD or some other sort of flash memory meant for all the writes.

Thx Rainer _______________________________________________ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos

Rainer Traut <tr.ml@...> writes:

Hi,

I am running C6.5 64bit on an USB stick connected to a HP DL360G7; It is usually an ESXi host but eg for firmware updates (not available on SPP) I use this local installation.

Problem are the lags and unresponsiveness we are seeing for example when running yum update in the installation phase. The whole system stalls but there is no io in vmstat.

<SNIP>

I've been running various versions of Fedora from a USB hard drive for several years and haven't seen anything like what you describe. I'm using a "real" 400GB Western Digital hard drive instead of flash or SSD. Given my experience I'd bet that the lags you're seeing are due to the flash drive.

Cheers, Dave