100 millions records?

I am trying to load couchbase with 100 million records for a test

I have cluster with two servers (8 core / 8 GB) and have allocated 6 GB of ram per each server. I am using a protocol buffer object as value about 450 bytes and key is around 20 bytes. I am already using the 2.8-preview3 client. I am using a singleton client from a simple test program running a simple loop that does both the read an write , so its just one single thread that does the write.
np101 and np103 are my cluster machines and I am running the client from np102 (0.021 ms ping)

I tried pushing in 100 million records , I tried the synchronous write function as I wasn't concerned about time it took I just wanted the the DB to be loaded up

I have a setup as described in my earlier messages.About 80-90% of writes seem to be timing out. I think it uses the DEFAULT_OPERATION_TIMEOUT (2500) which seems to be reasonably high. I am writing to it in batches of 1000. 15 million is the amount of records I could push with about 10 attempts.

I understand that we are limited with speed of disk I/O here still 15 million seems to be too low a number to get so many timeouts. What is the recommend server configuration for a setup like this?

Please find below the source code

public CouchBasePerfTestClient() throws IOException, URISyntaxException {
List uris = new ArrayList();
uris.add(URI.create("http://np101.xxx.com:8091/pools"));
uris.add(URI.create("http://np103.xxx.com:8091/pools"));
couchbaseClient = new CouchbaseClient(uris, "default", "");
}

public void callCouchBase(int arg) throws IOException, ExecutionException, InterruptedException {

long ttime = 0;
List profiles = new ArrayList();
for (int i = 0; i < arg; i++) {
final ProfileBuffers.ProfilePayload.Builder builder = ProfileBuffers.ProfilePayload.newBuilder();
buildValue(builder, i);
profiles.add(builder.build());
if (i % BATCH_SIZE == 0) {
ttime += batchWriteToCouch(i, profiles);
}
}
System.out.println(ttime / NANO_DIVIDER + " secs for " + arg + " writes");
}

private long batchWriteToCouch(int i, List builder) {
long ptime = 0;
List> booleans = new ArrayList>();
for (ProfileBuffers.ProfilePayload next : builder) {
final long putStart = System.nanoTime();
final String key = "xxxxx.net@1828383838" + putStart + i;
try {
couchbaseClient.set(key, 0, next.toByteArray()).get();
} catch (InterruptedException e) {
} catch (Exception e) {
System.out.println("error "+e.getMessage());
}
ptime += (System.nanoTime() - putStart);
}
final int failedCount = countFailed(booleans);
System.out.println(" batch write took " + ptime / NANO_DIVIDER);
System.out.println(failedCount + "writes in batch failed");

return ptime;
}